rough & wierd idle after engine fully warmed

[wolfort]

A wierd idle problem and it is intermetant (sp) and doesnt happen all the time.

Every once in a while, usually after a long drive when the engine was fully warmed, when I face a stop sign or red light, the idle seems to fluctuate up and down around 900rpm (brake at p gear), sometimes down to 200rpm and even stall.

This is very strange, because when it is cold, fast idle is ok(2k rpm), and when warmed it idles at 800rpm(brake at p gear) or 1100-1200rpm(n gear) perfectly. but when it's fully warmed after a long drive (usually 15min or more on interstate). it idles like a sh*t.

I began with what i am familar:no coolant leak, no oil leak, all fuses good, ignition coil ok, wire ok, distributor cap & rotor ok, spark plugs ok, fuel filter & pressure ok, air cleaner ok, choke & choke openner ok, coil ok, everything that i tested was ok.

I really do not know what to do next, I try to test pcv valve, but I can not pull it out.:( Im so weak!!. Too many vaccum lines to test everyone.
I belive it is carb related, could anyone give me some advice??
Thx!

[Mac]

One way to check the pcv valve is to gently pinch the hose while engine is idling. If the valve is good you should hear it clicking.

[HondaBoy]

i'd say you may have the same problem i did. a deteriorated vacuum line on your carb. its really worth it to look if you cant see it, feel the line for a hole with you fingers. i've noticed that my idle will go up and down after a long drive. not that noticeable, goes from about 1000 up to 1100 rpm, dont know exactly that thats all about, but it doesnt have any troubles like performance type.