I have a miss or something in my 93 pick up. I had just did a engine swap, run fine with only a slight hesitation at the begining of the rpm range, as the rpms gotr higher it picked up. Now it seems to be getting worse.
Here is what I have as miss or hesitation. It seems to come and go, not consistant at all. While driving it will be fine and then out of the blue it will start, then it will go away, then come back. It seems to have started after it has been a little colder out, might be a coincidence.
It does it any speed other than a the very begining of the throttle and full throttle. If I give it full throttle it accerates great, if I leave off full throttle the slightest bit it misses or hesitates and accutally slows down. Sometimes when I come to a stop it idles really rough like it's missing or something.
Timing is good and it has a brand new timing set installed by a ace mechanic, before I installed the engine. My average gas milage has been around 16 - 17 in town with a 24 mpg on a 240 mile highway trip ( that was before this started).
My check engine light was on from the start after I installed the ingine. I had installed the jumper wire to check for engine codes and got a 21 (o2 sensor). I did not get any other codes.
Would a bad o2 sensor be causing this problem? The only thing I did not put new on the engine was cap & rotor and plug wires because they looked fairly new and in good shape.
Any ideas or info would be helpful, I'm hoping it's something simple.
