Hi. I have a stock 1989 240DL with 112K that has a problem the local Volvo dealer can't diagnose. The car will randomly "stumble". What I mean by that is the Check Engine light will pop on momentarily and the tach drops to 0. The car then usually picks back up and runs fine until the "stumble" happens again. The issue occurs under all driving conditions (accelerating, deacclerating and constant speed - all weather conditions). Once or twice the car didn't pick back up and I had to coast to the side of the road. At that point, the car took a lot of cranking to start back up, but once running ran just fine until the next "stumble".

The local dealer said a "tune up" (plugs, plug wires, filters, etc., fixed a small vacuum leak, and ran some sort of cleaning solvent through the upper engine - to the tune of $700.00) would fix the problem - no change. Now they're telling me they did reproduce the problem after the "tune up", but can't diagnose it because the car isn't giving any codes..

Any ideas?? Help...

Thanks...