not everytime, but about half of the time when I drive my 1990 crx hf the idle will start to hunt while at idle

this is with the motor warmed up

the car sits and revs back and forth from 1200rpm to 1500 rpm rapidly.
(kinda like when you turn the AC on and the engine speeds up, only over and over)

the car is high miles and is all stock
I did replace the plugs, cap, rotor, wires, and 02 sensor recently

I'm leaning towards some sensor, maybe warm up sensor?
there are no check engine lights lit
also the fuel mileage has gone to crap when it is doing this, so I'm thinking its stuck in a cold start or warm up mode?

it has a stock catalytic converter, so another thought was plugging exhaust? but this is probably over thinking the situation.


Does anyone have any ideas or clues I should check?
thanks in advance everyone!

brant

 

check your vacume llines bro

 

Check your IACV And FITV, there are numerous threads on idle issues.

 

thank you both
I did not know where to look
I'll do some reading

brant