1990 Olds 98 Regency Brougham Running rough and stalling

[dksob81]

I am working on a 1990 Olds 98 3.8L, the car runs rough from initaial start up and after a minute or 2 it will start chugging and stall. I replaced the Plugs and wires

I have checked fuel pressure, holds steady at 36 psi. until it stalls then it goes up to about 42 psi. I did a back pressure test and it tested fine. Power balance test - found cylinders 1 and 4 were dead (no significant change when inj. were unplugged) check for spar and Cylinders 1 and 4 had no spark. Replaced the Coil Assembly and ICM and I now have spark on all cylinders but issue still exists. Will start everytime run rough and after a minute or 2 would die. I unplugged MAF sensor and runs a little better but still wants to start and die - it will die immediately upon plugging the MAF back in.
The customer got another MAF (used, which I recommeneded not doing, they didn't want to spend $150 on a new one) and problem still exist.

Any suggestions.
Also anyone have a picture of the correct wiring from the ICM to the COIL Assembly.
They said they had it replaced (with a used unit0 before I just replaced it again with a new one and I want to make sure the last person didnt get any wires crossed.

[maxwedge]

No codes I assume, so check for air getting in behind the maf, I assume it nows runs on 6 cylinders? Also check for the egr valve being stuck open. Basic diagrams can be found at autozone.com, repair guides.

[dksob81]

No codes.
Found the probem, The oxygen sensor was bad. It actaully broke off, must have happened when I put it back on the other day after I checked the back pressure.

[dksob81]

The original problem was the Coil Assembly and ICM, I'm sure. The O2 sensor must have cracked when I put it back on, after checking back-pressure, which caused a RICH condition which the computer tried to correct by cutting back on the fuel which explains the rough running, stumbling and eventually stalling. I did narrow the stalling down. The car would stall as soon as it would switch from OPEN to CLOSED loop, which makes sense because the computer pretty much shut down the fuel injectors (pulse width) to compensate for the RICH condition.