Hi guys (and girls)

I have a rather annoying problem with my W140 400 SE.
It seems that it only occurs when it rains (for several days). The engine starts and runs like usual when cold, but if I drive 7-8 km and park it for say 10 minutes, itīs either really hard to start or it wonīt start at all (and if it starts, idle is rough and it feels like not all 8 cylinders are running until rpm is above 1000 or so). If I leave the car for a while, it will start again.

I thought I had this problem sorted after replacing the crankshaft position sensor before christmas, but when my girlfriend took the car to the store last week, it happened again.

Iīve been in touch with MB who suggested the crankshaft position sensor at first, and now they wonder if it could be the coolant temp sensor (I have some doubts about that, as long as it only happens when air humidity is high).

Wiring harnesses looks fine, distributor caps & rotors replaced, spark plugs & wires have also been replaced not too long ago.

A friend of mine who runs a workshop has diagnoes the car several times, and he even tried spraying the distributor caps with water to see if anything happened, but - of course - it didnīt.

Have anyone experienced anything like this?

My 420sel Stumbles A Lot When It Rains A Lot But It Always Starts. I Havent Had The Prob Fixed Yet Though

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1984 300SD Orient Red/ Palomino
1989 560SEC
2016 Mazda 6 6 speed manual
1995 Ford F-150 reg cab 4.9 5speed manual