Just found the problem. A vacuum elbow going into the firewall by the evaporator for the climate controls was broken. Thanks for inputs

Finally this thing got bad enough to give a code. P0175 is the deal, system to reach. Anyone can guide me close to the problem. Appreciated.

Code scanners are fairly cheap (if you can't borrow one). If you can, hook one up and take it for a drive. When the condition occurs, go thru all the parameters that you can scan. It might tell you if your running too rich or too lean, etc.....

DEWFPO
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1998 S90 077,400 and 1995 964 154,100

I don't understand the MAF sensor being bad. The car has clean throttle and idle valve. The idle is perfect at 750 rpm when stopping going throgh town and in a short trip. This only happens after a long drive on the highway and then exiting somewhere and stopping at a red light. This has to be something else.
The MAF sensor would not be able to tell town driving from highway driving. Would it?

My 960 did this, and after a new O2, air filter, plugs, flame trap, the MAF was the cause. Expensive but this was the soln. Good luck.

On my '97, I cleaned the idle control valve and replaced a leaking intake manifold gasket. You can check the gasket by spraying carb cleaner, or something similar around the base of the manifold while the engine is in idle and see if it smooths out or increases rpm. I would try cleaning the valve first and then check the manifold...if the manifold is leaking try tighting the bolts first before replacing the gasket as the gasket can be a PITA.