I just bought a used 99 Durango w/ a blown engine. I have replaced the engine and when I drive between 40 mph and 60 mph the engine almost acts like it's hesitating or missing. It doesn't do it when it's cold, so I'm thinking it's a sensor problem since the electronics operate different in the open and closed circuit setting after it warms up. It idles great, and shifts fine, so I'm really thinking that it's a sensor. If anyone knows or has heard of this problem, please let me know. I'm currently living in Germany...stationed with the Army. Anyways, thanks in advance. Take care and be safe y'all. Fred

 

Welcome to the forum.

Might be a Throttle Position Sensor, or a Cam sensor.