88 SI Lude Idiling Problem

[homerj_1]

88 Lude Si 4ws 2.0 DHC FI Automatic
I am having a idling problem with my lude. Researched this site did not really find a answer so I thought I would Ask you Guys.
Idle is surging up and down after the car is warmed up Idles fine when cold but this morning started it let in run for about 10 minutes and it started going crazy up then down then up ETC. Hit the gas pedal and it straights out, Runs great down the interstate, Does not do it all the time just occasianly? Before this started I had replaced the plugs (NGK),plug wires, rotor button, It has a new Alternator, changed the oil and thermostat last week and yes I did bleed the thermostat, New antifreeze all new belts (including the timing belt)less than 6 months ago,
checked for a vacumm leak this morning, It has had the pcv valve replaced as well, replaced the computer about three years ago, Runs great no missing will get up go when I make it only happens after running it for a while or like this morning warming it up any suggestions thanks in advance.

[AcesHigh]

Wait... it idles fine when warmed up?

[homerj_1]

No Sorry let me be a little more clear. it is fine when cold starts surging after it is warmed up.

[AcesHigh]

Could be: Vacuum leak. Loss of compression. Bad head gasket. Old timing belt. EGR valve leak.

Just grab a Prelude service manual and it's all in there.

[rubix777]

I think there are a few threads on this already.

actually many things can cause the idle to surge, idle control or vacuum leak, o2 sensor,