[Beelzeburb]

The ECM is a 1227747, the sticker says it was remanufactured. I had just checked it the day before you brought it up. That ECM number corresponds correctly to the year and truck this engine came from. The ECM and the transmission have no connection to each other now. There were two wires from the ECM that did hook up to the TH400. One controlled torque converter lockup and the other went to a downshift control solenoid. I cut both of those because the 4L80E is completely controlled by the COMPUSHIFT unit (which works just fine, no problems there).

I've been working, testing and adjusting, but no change yet. I bought a Battery Tender Plus, so now the battery is fully charged and the starter spins the motor over quickly. I've checked for air leaks all around the intake manifold and found none. I followed the testing procedures for the EGR system in the service manual. The whole system checks out and functions as intended. I popped the valve covers off and adjusted the rockers according to factory specification (zero lash, then 3/4 of a turn). All of the valvetrain looks great, nothing broken, bent or misaligned. I unbolted the headers and applied a thin coat of high-heat silicone on both sides of the gaskets (a step called for in the instructions, but I didn't do it the first time around). That stopped the minor exhaust leaks I had had. I've always been careful to use sensor safe silicone on this engine. I replaced the spark plug wires with some that had more user friendly 90° boots. I even checked the resistance on the coil which didn't seem to give off the right readings, so it got replaced too, but to no avail.

It still needs starter fluid to fire up. It still stumbles and backfires out on the road. It still doesn't set any codes. It's still simply not running right. The symptoms seem to get worse when the engine is warmed up completely (well, to a point). I haven't completely run out of plausible components to check yet, but the 'normal' stuff doesn't seem to have been the cause so far.