irratic idle when engine is warm

can anyone help me, my engine is idling irratically, I have changed the sparks, gas filter which has improved the idle a little, however when stopping at lights the engine runs irratically. It is ok when it is being driven. I have been told to change the PCV (Positive Crankcase Ventilation valve). How hard is it to locate this valve, as on the haynes manual it is located behind the inlet manifold. Would appreciate anyones help.

pcv valve is just that. it recycles gases in engine back to the intake to be burnt out. located on valve cover.
check timing, feul pressure, and all vacuum hoses for
leaks. one vacuum leak could cause alot of problems.
if all that is good check egr valve , carbon deposites
in there will also cause this. do you have check engine light on?

Thanks for the response, the timing is ok, will check for the vacuum hoses. The check engine light does not come on. Should I change the PCV valve as well?

would not hurt very cheap part. were you able to find it? check engine light indicates an emmision problem, so that rules that out. still need to check fuel pressure,
just because it starts doesnt mean your pressure is good. trust me i found that out the hard way , on the interstate in alot of traffic. weak pressure means pump going dead, and believe me it picked the worst time to finally die.
good luck let us know how it all turns out.

The most likely cause is your TPS sensor located on the intake manifold. This controls your idle after warm up. During warm your IAC valve controls the idle. Try checking the coolant in the radiator to see if its full. The IAC valve is controled by coolant and that may also be your problem as is was the case in my Honda civic.

Thanks for all your help,
the problem was eventually solved, and it was the spark plug wires, they were arcing, causing the engine to sound irratic. However the sound was not like a normal arc where you can feel if the spark is missing. Hopefully this can help others if they have the same problem.
thanks again