Our '91 190E has a problem which occurs on starting. The severity is proportional to the length of time between starts, and is not noticeable on restarts the same day, and usually not after a 24 hr rest. After a 2-day rest, though, the symptoms occur: starting is immediate, but the symptom is running on less than all 4 cylinders and threatening to stall. This persists usually until starting to drive down the street, or for a couple of minutes, then all is fine.

So far, after a 2-day rest, I removed the plugs. All appear fine and similar in appearance, with no raw fuel smell. Started up then for just a few revolutions, then turned off. Still no raw fuel smell on any plugs, even though symptom was present. I do detect a possible slight hint of dampness of some sort on plug #4 threads.

Since coolant level goes down over time, and most external leaks have been corrected, I believe, my first thought is a gasket leak, even though the head gasket was previously replaced about 40k ago. Anyone have thoughts of other possible issues?

Thanks, Steve

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'91 MB 190E 2.3
'08 RAV4 Ltd 3.5
'83 Lazy Daze m'home 5.7