Help! Another bad idle/hesitation problem

[Mike G]

Hi,


I have a 1991 500 SL with 115,000 miles. Car runs fine. I recently replaced plugs, distributor caps, rotors, oxygen sensor and had injectors cleaned.

Car ran great until about three weeks ago. The car was driving along great -- but then suddenly engine stumbled badly. From then on, it hesitated slightly at about 1000 rpm just as it pulled away from stops. The problem did not appear the next time I drove the car.

Last week it did it again. Then it ran perfect for a few days. Now it is happening every other day. The problem is getting progressively worse-- the hesitation is now more pronounced.

Yesterday, I started car and it would barely hold idle. Lights dim and brighten as idle drops. The car hesitated badly as I pulled away from a stop. About 10 minutes into my drive, I heard a screech (belt???) and problem disappeared.

Today, started car and, again. it barely held an idle. After a couple of minutes, it idled better but still a little rough. It hesitated after every stop. About 15 minutes into my drive, problem completely disappeared. When I arrived at my destination, it started doing it again.

I have searched the hundreds of idle and stumble postson this site, but none seem like mine where it comes and goes.

Any ideas? Any help would really be apprecated.


Mike