if it was really bad it could lean out and melt a piston.

That may have something to do with the smoke at high revs when the engine is warmed up? And I'm also still losing oil, could that possibly be to do with it? I don't think the engine is stuffed in any way though because it still goes good and I even forgot to put the oil cap on and it didn't lose any oil. I even raced my mates modified R33 Skyline yesterday and beat it.

Then id say your tune isn't really bad.

Using oil is just how things go with old motors. How many k's has it done?

Smoke could be worn rings due to age or over fuelling for safety.

No idea how many kms the engine has done, because the guy who owned it before the guy I bought it off changed the engine and didn't now how many kms was done on it. But it never has any oil on the oil cap so I guess that means that the oil pressure is good.

So the smoke could be from it running rich from the ecu tune. And I only have 10w oil, maybe I should use 15w.

10w a single weight?
Or a multi weight oil

If your running a 10w I wouldn't be racing anyone it will give the engine no protection at all..

But if your running a 10-40 or 50 that should be fine..

10 only means when it's cold and the. Second number is how thick the oil so the 10 would become as thick as a straight 50 is once warm to give you added protection for when you give the engine a hard time..

Used 5W40 and drove the car flat out at Winton Fun day
Edit: Used Penrite HPR 5 (Synthetic)

So lucky you live close to a track ahah damn you :p

Anyways yeah I'm changing to a 5-50 my engines getting a little old so of prefer a bit thicker
Got some martini racing oil on the way in the above weight see how that goes
Use to run 10-40 royal purple that was pretty good just prefer to have something I can use on track and on street with out have a lot of drag.

With your idle problem does it only happen when cold or all the time? Odd's are its you steper motor (idle speed controller).
You have an afermarket ecu but didn't get it dyno tuned? why? You probably dropping heaps of power especially if the guy who installed said it's in need of tuning.
Anyway with your oil going thicker isn't always better, you have to get the right oil dependant on the size of your oil galleries and bearing clearances. If you have large oil galleries and run too thin an oil, the oil flows too fast through the engine, also older engines tend to run larger bearing clearences so too light an oil is no good for that. Same problem if you run too thick an oil on newer engines with smaller oil galleries, the oil will flow too slowly. Best to check with 3s engine builder on their recommendations. For reference I'm running a 5-40w in my race car.
 

A local mr2 guru recommended 5-50 martini it's what he's always used in his street and track mr2s
And also mine has 220kms has 185psi across all 4 cylinders had a head rebuild 20xxxkms ago but not a bottom end rebuild did burn a little oil but not a lot
So I'm following his recommendation and running a 5-50
Many people I have spoken to with mr2s run a 20-50 royal purple and toyota recommend a 10-40 I believe or a 10-30
But that was new.

It's happens all the the time. I use 10w40 which is what the computer at the shop said to use, but that's not knowing how many kms my engine has done.