I have a 91 F150 with a 5.0..it has 127 miles on the engine and tranny. I did a complete rebuild..everything is brand new.. I had a rocker arm bolt break and had to go in the other day and replace it. When the rocker bolt broke..it sucked up oild into the cyl snf it smoked like a train. Now it wants to hesitate when you stop or start at redlight. Could the o2 sensor be sooted up from the oil? What else could it be? I am thinking about cleaning the o2 sensor,and plug for that cyl, and then resetting the computer..Any thoughts? Thanks..Joe

 

Throwing any codes? Check there, and get back with us. If it's stalling/running rough, check all the usuals. Was it doing this before? Etc. Describe the break-in period. Warranties?

 

Well if you have not already I would throw a new spark plug in their and yeah you could be right about the 02 sensor if their was allot of smoke. Just pull it out and give it a clean. If it has not been replaced in a long time you could always throw a new one in their. You are supposed to change them every so many miles anyway

 

yea i replaced the 02 sensor and every part on the engine..all sensors have been replaced except the EGR valve..i will clean it too just in case.

 

Could be a vacuum leak.

 

If a rocker arm bolt broke then there's probably a reason for it. Are you sure the timing is set correctly?

 

How about the fuel filter?