Hi all, sorry If not allowed but run out of talent and didn't get any help anywhere else!

I'm from Europe and specialised on BMW-s, now fixing a 4gen 1996 3.8 v6 camaro for a friend.

The main issue was: the oil went in the water and the engine didn't run properly, it was keep stalling and had a bad reaction for the throttle.

He was told all the issues caused by the intake gaskets so I replaced everything for him, but the idle and throttle issue is still there. When you floor the throttle, it just stalls.

I wanted to make a diagnostic through the obd2 port, but there was no response from the diagnostic port unfortunately.

We ordered an ignition coil and started to change them one by one but obviously all the cylinders are running now even though it keeps stalling.

After the igniton coil replacement, it started running differently, after start up it revs up upto about 4000 and then it slowly stalls.

I unplugged the connector of maf and throttle position sensors, and it didn't make any difference.

My question is:
-does anyone have a clue of what the issue could be?
-why the obd port is doesn't work with my universal diagnostic tool? We've checked all the fuses and they're okay!
-where the ground cables are located that is responsible for the engine management?

Thank you!

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