Help Please Read 4.0 engine question

[newguy06]

i just replaced my engine in my 91 explorer with an engine out of a 94 ranger, the guy i bought the engine from said that the motor had been out of the vehicle for a year or so but it was garaged and covered, and when we put it in the explorer we exchanged the intake with my stock one and it started right up.

Ok to the question, after running the motor for a few minutes while fixing vacuum leaks we started hearing a sputter or backfire on the passenger side, we replaced the plugs, wires and checked the coil but that hasnt fixed the problem. When the car is warmed up you cant even make it up a hill because of the sputtering.

I had a friend come listen to it because he knows some about cars and he said to let it cool off and start it again so we did and it didnt make the noise until it warmed up, the weird thing is when you disconnect the cruise control vacuum hose the noise stops and it idles fine but when we tried to cap the line the car wouldnt even move it would just idle in neutral.

I am losing my patients with this problem and im hoping you can help me?

 

[Positive Vibes]

I think your on the right track, it sounds like a vacuum leak.

The only time my truck would run the way you described was due to vacuum lines being disconnected. I would double and triple check your vacuum lines.

 

[newguy06]

but if it is a vacuum leak why does it only do it when it warms up? My friend seems to think it is a valve sticking, do you think this is possible?

 

[Positive Vibes]

but if it is a vacuum leak why does it only do it when it warms up? My friend seems to think it is a valve sticking, do you think this is possible?

Not sure. Thats getting over my head.

Maybe 410 will chime in here. If not send him a PM.