Can an ECM only "sorta fail"? i.e. runs but won't switch on fans, runs erratically (tachometer all over the place). And if i disconnect the MAF, the ecm runs off of programed voltages, right? My car is acting nuts!! I get a code 33 and 36. 33 goes away if the maf is connected and codes are cleared, but the car will NOT run w/ it connected. I've replaced the ign module, cap, and rotor, but the car is still possessed!

 

LaCrosse,

There are a couple of issues at play.

If you're using the 305TPI programming with a 350, you're going top get a '33', since the ECM is going to expect the air flow rates within the range that was programmed for the smaller engine. You may be looking into a 350 PROM.

As for the stalling when connecting the MAF, you should probably connect the MAF and a digital voltmeter to read the MAF output voltage at a given RPM. The results could be enlightening.