Hello, I wonder if someone can help out. The car is a 1987 260E 2.6L engine. Recently starting to have weird problem, worrisome enough that it is garaged now and not taken on the road anymore.
When cold in the morning the engine starts fine, runs fine. Then as the engine warms up (15minutes later) it starts to run really rough, and the exhaust is all black such that it would leave the pavement underneath it black with sooth too.
When this conditions is reached, if I put some load (pull the throttle to up RPM) on the engine and release the load (let go of throttle), the engine would stumble a bit and shuts off, then I can't restart the car at all, it would crank and crank but the engine won't restart. Come back in a few hours, the car would restart, and the whole procedure can be repeated
You can see why it's scary and not recommended to drive this until the problem is fixed. Say I stop at the red light, the idle will go up and down and up and down and scares the hell out of me, sometimes it would just stop and wont start again. Luckily I made it home and now keeps the car in the parking lot until I can fix the problem.
I started to fix it by first replacing with a new set of spark plug. Didn't help. Next? maybe replace the distributor/rotor set?
I am suspicious of some temperature related issue. Would a bad temperature sensor cause this?