Everyone,

I have been diagnosing an on-going issue with my wife's '94 940 Turbo. I have been slowly doing a level 0 on the car, but this issue has been persistent. The main problem is that during hard acceleration (especially when cold or under load when going up a hill for example), the RPMs will surge and you will get pulses in the acceleration of the car. You can see this on the Tach, the RPMs will surge by as much as 250 when the problem is particularly bad. Only other issue with the car is a wandering idle that stubborningly sticks around, despite cleaning of the throttle body and IAC. What has been done so far:

- Recent stage zero (~1 year ago): new plugs/wires, new dizzy cover, new timing and accessory belts, IAC and throttle body cleaned, PCV system cleaned, vaccuum lines replaced with silicone.
- New turbo (replaced due to large throttle shaft play and whining noise)
- new ignition coil
- Relatively recent (~3 years) replacement of RPM speed sensor on the back of the block

I'm some what at a loss...I am thinking of trying a new IAC to help clean up the idle, but I am not sure if this could be causing my acceleration surging. Only other idea I had was that I was getting intermittent knocking during hard acceleration and the timing was being retarded, causing the surging. Is there an easy way to see if the knock sensor is detecting knocks? Any other ideas on possible sources of the problem?

Thanks,
Brian