Engine Performance problem
2002 Ford Expedition V8 Two Wheel Drive Automatic 123192 miles
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The engine only surges when I am sitting idle at a red light or stop sign with the A/C on. It surges for about 10 secs intermittently then stops. Any help with this matter will be appreciated.

Hi sailor1969,

Check for any vacumn leakages after the throttle body valve.

Check PCV from valve cover.

Is the check engine light showing?

Replaced the PCV valve and checked for vacuum leaks. Engine sounds quiet but for the AC compressor kicking on. Unusually quiet actually. Took it down the road and the same problem is still there. I did notice when you are sitting in park then give it some gas and bring the rpm's up to around 1500 then quickly let off the accelerator, the rpm's drop low and the engine starts acting like it wants to shut off before picking back up again. I checked the throttle body to see if it was sticky in any way but it releases and bounces back very well. Also, the check engine light has never been on but I'm tempted to take it down to the parts store to have it tested anyway just in case I can get lucky.

Hi sailor1969,

Your description of the symptoms is similar to insufficient valve clearance or valve leakages.

I would suggest giving the throttle body, especially the idle circuit, a good cleaning if you have not done so.

I was a little worried about the valve clearance problem so I went to the nearest auto part store and purchased fuel system cleaner (x6). Followed the instructions and the hesitation has stopped along with the rpm idle being erratic.