My 1989 Dakota (3.9 V6, California) started running rough when cold. This problem progressed and I'd have to get it hotter and hotter before it would run smooth. Finally, it wouldn't run at all. From different suggestions, I've put in a new Distrib. Cap and Rotor, new Fuel Filter,new MAP sensor, new TBI's, and I've checked EGR and PCV valve. About to change wires, but before I throw a lot more $ at new parts - like O2 sensors, TPS's and such, I'd like to know what might be wrong. This thing is so instantaneous, it's almost like somebody flipping a switch back and forth, which makes me think it might be an electrical prob.

The mechanic I have it with now is saying it's the computer (ECM, PCM, SMEC or whatever you call it). Does that sound like the likely cause of this problem that got worse and worse? If it IS the likely cause, which ECM should I get - I've heard it's a bit cheaper to get the non-California version (and that it still works fine and the engine runs better). Will it interchange with the Ca. ECM and run with no problems?

Also, have any of you been busted by a smog inspector (or his seeing-eye dog) for a non-Ca. ECM? Is it just a sticker on the top that they check during the "physical inspection"?