Whether my truck is cold or hot, when i just start it it runs fine, the idle seems to be a little high though. It will run good for like 3-5 minutes and then the idle drops down like it will stall and then it surges really bad like it is going to die and then it surges strong and goes right back into the stalling sound. It will do this for a few minutes and then it will go back to idling like it did right out of starting, smooth but a little too high. I have put in a new plugs, tested the wires, changed distributor cap and rotor, put in new fuel filter, and also cleaned the iac. The truck still continues to do it though. By the way this is a 97 f250 hd 5.8 v8/ 351 and it is a 5 speed 2x4. Thanks guys.

 

I see you cleaned the IAC. Did you also clean the Throttle body?. This condition is constant? does it happen everytime you use the truck?.

 

Did not clean the throttle body. I may try that thia weekend. Like I said it runs good a little while then it runs the way i described and come back after a while but then its fine until I shut it off and start it again. Yes everytime I use my truck. Thanks.

 

Have you checked for codes ? How bout Vacuum leaks ?

 

I havent found any vacuum leaks and no codes other than oxygen sensor when i am driving it

 

97 HD 351 OBD 1 ? Does it only have one o2 sensor ? I have seen bad o2 sensors in a one sensor set up cause similar complaints .

 

There is only 1 oxygen sensor. Yes it has obd1

 

I would change the o2 sensor to start .

 

I would retrieve the codes first to see if the computer gives any info on the sensors.