2001 VU V6 Ecotec Auto, running rough!

[Damo2550]

Did you change the fuel pressure reg as mentioned earlier?

Ah yes I did, I thought there was one more I had to add to the list of changes made.

 

[Damo2550]

Here’s an update on the VU,
So the things I have changed (one at a time) to try and find the issue.
Replaced all these, injectors, IAC, cleaned the throttle body, new spark plugs and leads, coil pack and DFI, Throttle position sensor, checked fuel pump, drained the tank and replaced with 98ULP, tightened the intake manifold plenum, checked the evap purge solenoid, and the AC/Heater vacuum control tubes. All injectors are working and spark plugs doing everything normal.
Engine still runs rough and starts producing Smokey fumes after a while as the engine gets warmer.
Also no engine light appears but yes it does illuminate before starting with all the other lights when you turn the key as normal.
Before I look at replacing the ECU and buying an ALDL reader, is there anything else that could be causing the problem, ie, Catalytic converter failing?
Am I missing something? Does it need a tune?
Any help or advice will be greatly appreciated.
Cheers people!

And the fuel pressure reg was also changed.

 

[Dak]

Why was the top end rebuilt?? Cooked? If so you were crazy not to do the bottom end, rings will have lost all their tension.

 

[Damo2550]

Why was the top end rebuilt?? Cooked? If so you were crazy not to do the bottom end, rings will have lost all their tension.

Hmmm I did wonder about that but it wasn’t cooked. It was initially thought that the head was cracked so when I bought the car I had the heads machines, new valves, clearance checks done and all cleaned. The machine shop said the heads were actually pretty good. A compression test was done and had between 141 and 134psi across the six cylinders. I was told that was good so I didn’t bother doing the rings.
I’ll do another compression test myself and see what I get. I did think maybe a valve wasn’t working so I took the cover off and rotated the engine and all valves are working ok.