In the fall, after I installed the winter tires, I noticed that the car would downshift while in cruise control mode on sections of the four lane highway and it did not do this with the summer tires. I just thought that it was the higher rolling resistance of the winter tires (although I did not notice this the winter before). But since that time the car seems to be getting nosier, is now downshifting into second on portions of the four laner, seems to have less power, and last night on the highway it lurched sharply three times over a period of one hour at 120 km/h as if a cylinder or two suddenly went off line and then came back on. The lurching felt like gear lash on a car with a manual transmission. This lurching also reminded me of a K-car we had after it developed a head gasket leak. Last time I checked, all the fluids were clean, no cross contamination. Couple of things: the rear muffler was very badly corroded and I patched it last summer but now I wander if the guts have collapsed and are causing back pressure, and I noticed a muffler sound around the cat where there was none before, so I wander if I am developing a hole in that area or the joint is starting to leak.

Any help in troubleshooting is greatly appreciated.

92-960, 200 000 km

See the 700/900 FAQ under "960" for information on various problems. It sounds as though you may be beginning to suffer from ignition harness rot at the coil pack connectors.

It sounds as if the car is actually having some kind of power loss, and you're pressing the accelerator more to make up for it. You could have a vacuum leak, and in this car, that's likely to be just the intake manifold. Try tightening the nuts- it may help some. May need a gasket. Also, the plugs could very well be on their way out. They should be changed every 25-30K. The car may will run with higher miles on the plugs, but worse and worse- as you may be seeing. They take an unusual plug. Order it from FCP or another supplier or risk paying triple or more from another source. Also, just make sure your air filter is not plugged up. I assume you aren't having a check engine light, or blinking lights on the transmission shifter switch- either of these would indicate the computer has already diagnosed a problem and has a trouble code stored.

Good luck with it- I'm sure that you'll get to the bottom of it here soon.
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Rob Bareiss, New London CT ::: 86 244DL, 87 244DL, 88 744GLE, 91 244: 808K total