95 V8 Dakota, runs very rough when first started in the morning. Missing, backfiring, stumbling, ( Summer or Winter ) until warmed up, about 5 mins. or so. After that it runs REAL good. Not the E.C.U. I checked that and other sensors, except the coolant temp. sensor.( It's a P.I.T.A. to get to) A friend said that it could be it, since it only does this when it's dead cold. Could that be causing the problem? It even runs good after it sits for 4-5 hrs. Only acts up when it sits over night. Any thoughts?

 

It could be the ECT since if that's lying, the ECU MAY decide the motor is warm, and that'll cause it to stumble something fierce.

Since you've not tried that yet, I'd replace it, especially since it's, what, 23 or 24 years old?

RwP