My 95 F150 with 89k miles has a 5.8L eng that has an idle surge up to abt 1k rpm and then slows down to almost cutoff and then surges back up. It stops surging after a few minutes of warm up and levels off to a smooth (approx) 600 RPM. It had a check eng light on also. I replaced the O2 sensor which cleared the check eng light and made an immediate improvement in highway driving smoothness. Afer replacing the o2 sensor it still has a code po 179 and still has the idle surge. Any ideas? TKS

 

I had the same problem, plus I had a hesitation when I accellerated. The fix was to replace the Idle Air Control Valve or something like that. Basically, it is the Idle control pretty easy to replace. I had 70K on mine when I replaced it.

 

I had a similar problem and it turned out to be partly due to the TPS (throttle position sensor). My truck also had a bad altenator which didn't help with the surging problem. It would surge high and then just about stall. I had both the altenator and the TPS replaced along with a couple other minor things and it's been running great for the past month since then. My truck has about 120,000 miles/182,000 km on it and this is the first that any of these things needed attention, so i guess i can't complain.

I would check on the TPS and see how it goes from there.

93candycane

 

Thanks guys I'll check both suggestion out.... I'll let you know what is was when I fix it.