Over fill engine with oil

I recently changed the head gasket, main oil seal and other gaskets to stop my 1990 740 Volvo Gl with 260,000 from leaking oil. It started great afterwards, but it wants to stall out if the RPM’s go less than 1500. I rember that I had mistakenly added 5 qt.s instead of 4. Would this cause the stalling and aputtering I am expeirencing

No overfilling the crankcase would not cause an idling problem. You might look for a vacuum leak or broken or leaking hose.

Well … Maybe, but somehow I doubt it.

I suggest that you check the level of oil and get it back to normal right away. Too much oil can damage an engine. However what you describe would not by a typical response to too much oil. I kind of like Researcher’s suggestion of a possible vacuum leak. I don’t know if he is right, but it is worth following up.