First time posting here I have just spend I guess 2 hours reading these great posts here. I wish I had found forum like this before. Good job who ever is behind this

My problem with this car comes and goes.

Car is US model E300D 1996 106k miles

When I drive over 40-45 miles per hour some times my engine rpm starts to go up and down and won't level out until I either release gas pedal or push more it. When I push more I can hear my injection pump making very hard "knocking" noises and black smoke comes out from tail pipe, not much but I can see it from mirror.

After this car might be ok for minute or two and then it will happend again.

But some times I can have one week and no problems.

When I have the problem week, gas mileage is very poor 20 or less miles per gallon.

Problem is only with speed over 40-45 miles/hour with highest gear on. With 3 gear on problems start with speed 30-35 but not with speed 40-45 but car will have hard knoking noise from pump and some black smoke.

I don't think it is my fuel injection pump because I had recently it tested and seal replaced because it was leaking fuel and they said pump was fine. This was done by local diesel pump repair shop.

I also have problem when I turn my engine off my engine won't shut down right away some times it might run up to 1 sec "roughly" before shutting off and then some times check engine electronic light comes on but will go away after 50-100 miles of drive. I think its problem with magnetic shut off valve but could this also affect the engine rpm when driven?

I have had older diesel models before and I could pretty much fix them my self, but looks like this might take me down... and I have to go to MB shop...arrggg

Any help would be appreciated!!!

I have OBII reader but when I used it when problem started first time it did not have any codes. I have not have change to use it lately.

Thanks, Vesa