Howdy,

My '93 240 has been having a number of troubles recently and the latest is an engine issue which I am having trouble diagnosing. It is very random and started a couple of weeks ago. I was driving on our local highway at about 120 km/h when my rpm's spiked suddenly about 3 times in a row and then the engine stalled. I pulled over and the car started and ran fine. It did this a few times so I drove back roads for the rest of the trip (about an hour in total).

Drove around town all weekend with no issues.

Then on my return journey, it started doing the rpm spike/stall thing over and over while driving above 80km/h... then it eventually just happened at any speed. I stopped and found that two of the spark plug wires were loose so I rigged them up with a little dielectric grease (for suction to keep the wires connected - the connector ends weren't clicking on to the plug ends). No issues the rest of the way home.

When I got home I ordered new wires, plugs, cap, and rotor. Did a full tune-up on Saturday and the car was great for just under 15 minutes (pulled really strongly) when it did the rpm spike and stall again. This time it was very erratic and started running very poorly after the stall. I also lost power 3rd gear and up... car was bogging down and had very little get up and go. No more stalling but was difficult to drive. I had to get where I was going so I took back roads again for about 1.5 hr drive.

I let the car sit over night and drove it yesterday for about two hours. First hour it was very sluggish and then by the second hour, it was driving fine again. No rpm spikes or stalls at all. Very strange behavior. Any ideas?

Also, the old plugs were a blackened, smelled like oil, and the firing pins were whittled away to a very thin point on each plug.

Thanks,
Clayton.