Hi All,
From my searching, it seems almost compulsory that Gen2 3sgtes with stock fuel systems run rich.
It also seems common that the Fuel Pressure exceeds the BGB specification, so I am about to embark on the “fit a gauge to the fuel rail” exercise to see what’s going on. But first I thought I’d check with the collective experience here to see if the regulator is likely to be the cause of my richness. ? 
Last dyno run shows AFR is 13:1 at 2000 rpm, inctreasing quickly to 11:1 at 2800, then a slower but constant increase through the range (10:1 at 4700, 9:1 at 5900). Torque declining from 5100.  Does a faulty regulator (tired spring?) generate that sort of increased injection ?
I should add that I am presuming “stock fuel system” and it probably is, but perhaps the pump and injectors are not.  The ECU is definitely stock.
Any tips or advice, gratefully received…. thanks

My tip is to check the ecu capacitors before doing anything else. I had running rich issues and i had two blown caps.
 
After the caps were replaced the car was fantastic. 

IMO - varying factors to engine mods, boost level and servicing. Generally (basics);
Get injectors ultrasonic cleaned and flow checked for flow and spray pattern/atomisation. Injectors Online in Melbourne is my recommendation.
Check Air Flow Meter screw, or can be used in dyno tuning to lean a little.
Check o2 sensor
Check TPS
Check/replace spark components (higher boost than stock possibly need colder spark rating)

Mechanic should be able to hook in a fuel gauge to check fuel pressure.

Stock ecu/engine and under acceleration should not run stoich, it should run rich. Many stock ecu/engine will run rich as you described, again many factors that vary that make it run rich or richer.

Thanks Guys,  appreciate your time.
I recapped the car (and my 2001 Camry) about 9 mths ago, and both cars improved slightly but noticeably , especially driving off idle.
Injectors have been done. AFR screw is a couple of mm more than factory setting. I put it back to the factory setting and soon had the car cut out a couple of times when idling at lights, always restarted straight away and usually didn't cut out, so I put it back halfway to what the previous owner had set it to. But isn't that for idle mixture control, which is not my problem, I am at my richest at top revs wot. I forgot to mention, I am only getting 9psi boost at the moment.
 O2 sensor is new (a year?) but had to cut and solder wires to fit a 4wire version. That is a possibility.
Haven't checked the TPS. I am running 1 grade colder plugs, don't think that is the cause.
Yes I understand turbos under load do not run at stoich, and should be somewhere between 11 and 13:1, I think, but mine is dropping into the 9's. Am about to build a boost leak tester and then fit a manual boost controller, to restore the boost to 11psi, (and later to 14). The low boost may be responsible also, will know in a few weeks time. I just wondered whether the fuel pressure could be possible cause.
Thanks again....

I've only tested two stock original fuel pressure regulators and both were Gen 3. and both were way below spec.
One engine had it's ring lands ruined and I can't but think fuel pressure could have contributed.
Good idea to get a fuel pressure gauge into the cabin so it can be monitored.
Might be an idea to check that the injectors are the correct ones for the original ECU fitted.

Thanks Falcon, next time I get the rail off I will check the injectors. Are there markings that identify them?
Re the 2 regulators you checked, and the lean running to destruction which is not my (current :o) problem, hadn't thought of that, but scarey. Perhaps explains the stock regulator spring exceeds the BGB fuel regulation to safeguard against aging/weakening ?  Either way, your story makes a compelling argument to go ahead and fit a fuel pressure gauge to check the operation periodically. eg each dyno run.
 Don't really want extra gauges in the cockpit unless via a touchscreen where the radio is. (That'd be a cool project for my son). For now will set up an attachment on the fuel rail where the gauge can be swapped in/out with a bolt. cheers,

Great information contributed to get you started. Old vehicles like Mr2 need some tlc.

Falcon has a very impressive set up that I think looks great, not sure of brand or supplier, it displays all the information to keep an easy check of engine conditions - and no mucking around with long menus etc. in touch screen scenarios just easy to read display that looks fitting with the interior.

Check out JRP Multi Gauge for very reasonably priced set up.  Very compact to install and has a lot of parameters covered with safety alarms etc. Your son would love setting it up. Dave is great to deal with and very helpful.
I fitted the duel screens as I wear long distance specks for driving and they allow the figures to be displayed larger.
This instrument pack has allowed us to diagnose several problems over the last 12 months or so.
It's also nice to see all the good numbers up there moment to moment and when very busy on the track it's great to know that an alarm will warn you that something is straying beyond it's normal condition before it causes problems.
I have a glance at the air/fuel ratio as it accelerates down the straight in 4th gear.
Nice to see the fuel pressure instantly climb as the boost goes up too.
A great bit of kit. Very entertaining.

TonyMR2
Falcon has a very impressive set up that I think looks great, not sure of brand or supplier, it displays all the information to keep an easy check of engine conditions - and no mucking around with long menus etc. in touch screen scenarios just easy to read display that looks fitting with the interior.

https://www.justraceparts.com.au/10in1-automotive-digital-oled-multi-gauge-display

Does it need a raft of new sensors installed, or does it run off or tapped into the stock wiring ?
It does look useful - especially if it includes alarms....
I have flicked it on to my son to see if he wants to do this.