Poor Idle

I was wondering if any veteran volvo owners can help. Ive got a 1994 940 wagon B230f and when it's idling the tach (and engine) bounce from around 400rpm to 1000rpm. It gets worse when in gear but does it in park too. It doesn't happen when cold but once it warms up it acts up. I replaced the headgasket cause there was coolant in the oil but that didnt fix it. I took out and cleaned the idle air control valve, and nada. Do I need to replace the coolant temp sensor? Or was cleaning not enough for the IAC?

Any feedback/help would be greatly apreciated thanks!
- Theo

With the needle bouncing I would say ignition

So what? New coil? distributor? I just replaced the plugs and wires with the headgasket.

I would try the dizzy first, or both, they're not that expensive but go with a brand, I've had some bad experiences with el cheapo stuff lately.

Check for vacuum leaks. Use Bosch ignition components and sensors to keep it from being fussy.

KeizerBrickGuy said:

Check for vacuum leaks. Use Bosch ignition components and sensors to keep it from being fussy.

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+1. I was chasing a similar issue with my 240. After changing a bunch of stuff, found a small hole in the intake accordion hose. Once that was taken care of, surging idle cleared up.