Please accept my apologies if this has been discussed/covered. I attempted to search threads for posts pertaining to my inquiry, but to no avail.

(Moderators, please feel free to re-direct or re-post this in a more appropriate thread if necessary, thank you.)

The A4LD gave up its ghost so I decided it was time to do the M5OD conversion. Before the conversion, I would warm up and run the 3.0 engine once in every while during 3-4 months between the time it broke down and when I was ready to pull the tranny off with no apparent negative effects.

However, once everything was hooked up and ready after 3 months, the engine would start up fine but after 5-10 minutes of idling steam/smoke (not exhaust gases) would start emitting off both sides of the y-pipe causing me to become alarmed and shut the engine.

I checked and adjusted the timing (it was firing at 20 deg BDC after the conversion, it's back at 10 deg) but it still is giving off light smoke off the surface of the y-pipe. It makes me think that it's running lean because if it was too rich, the catalytic converter would turn cherry red like it once did many years ago before I had injectors cleared and cleaned.

I have yet to drive it around in fear of destroying the engine.

I thought about swapping out the ignition coil but found that it's the same for both automatic and manual models so that leaves the ECM/PCM.

Would swapping out the automatic ECM/PCM to the manual model help or am I just overreacting/over analyzing?

I thought about the old fuel, maybe it was causing to run lean but it was running ok when I warmed up the engine occasionally before the conversion. Also, I added a bottle of fuel cleaner along with a couple gallons of premium fuel (the tank was holding 85-octane when it broke down on me in the middle of Arizona desert last summer).

(Haven't filled out my signature yet but it's '91 3.0 Reg Cab, 7' Bed, everything stock.)

Looking forward to any inputs, thank you.