Hey guys, decided to replace the rocker cover gasket on my latest acquisition, cleaned intake plenum and T-VIS plenum, masked and painted, put everything back together,
Started, runs and drives fine, yet the idle is erratic, on startup idle is 2K rpm then hunts rapidly 1800-2000 cyclically, threw fault codes 21, 41 and 51, after a reset, issue is still there but no longer throws any codes, can anybody shine some insight light on the issue or experience the same problem?

TL;DR?
Idle is erratically cycling 1800-2000
No fault codes
Plz halp?

Theres a chance the codes (or some of them at least) were there prior to this issue.
 
21 o2 sensor
41 TPS
51 Switch condition signal-no idle or ac signal to the ecu  BGB talks about a 'Trouble area' being the TPS, ac switch circuit/amplifier.
 
Is there any chance the TPS isn't connected properly?

TPS is definitely connected properly

Probably a vaccum leak.

Idle speed control valve ???

Vacuum leak is what I'm leaning towards, but can't find a rev 1 vac. Diagram

When you say Rev 1 3SGE, are you referring to a Gen 2 3sge motor?
Anyway, here is the Gen 2 3SGE diagram.
 

Any chance you have the gear to do an intake pressure test?  It's amazing/worrying how many leaks you sometimes have.

5SGTE
Any chance you have the gear to do an intake pressure test?  It's amazing/worrying how many leaks you sometimes have.

Unfortunately I'm not that lucky haha,
Although it is worrying I'd like to think that it is ruled out, considering that it got gaskets and the mating surfaces looked great, also torqued down to spec as per BGB and in sequence 3 times over.

Reddtarga
When you say Rev 1 3SGE, are you referring to a Gen 2 3sge motor?
Anyway, here is the Gen 2 3SGE diagram.
 

Yes reddtarga! That's the one, thank you for the course correction there and thank you for the diagram! =)