Hi, my mom gave me her 1987 240dl w/4 spd auto last week. Looks good but needs some work.

It starts up easy and idles pretty good, but once I'm on the road it won't go over 35mph. It doesn't lurch or hesitate, just lacks power and the engine won't wind up.

I checked the sparkplugs, whitish tan color. I replaced the dist.cap and some burnt looking wiring going to the temp sensor under the intake manifold. I also checked for vacuum leaks with propane and didn't see anything unusual.

I took the air filter off and noticed that the cover had not been properly attached. The plastic elbow leading to the amm has evidence of water and mud. (not much) She lives at the end of a dirt road that can get pretty muddy in the winter. I was wondering if water and dirt could have ruined the air meter unit causing this problem.

Possibly the cat converter is plugged and will check that next. (take it of and look through it?) I guess also could be the fuel pump or the relay.

Anyone else have a similar problem? This is a neat old car that I want to keep going! Thanks.