1974 450SL running problems

[RPSmith]

I really want to save this car, but the problems are mounting. It died last summer and took it to a mechanic. He diagnosed the transistorized switching unit was bad. Very expensive part so he put on an optical ignition in lieu of the points. He also changed the plugs and wires.

It ran for a day and then started with white smoke out of the tail pipe and wouldn't idle. It will start but I have to keep my foot on the gas keeping the idle high. Turns over a long time before if begins to fire slowly and then I have to give it gas to get it reving high. If I let off the idle drops and stalls out.

Engine only has 70,000 miles on it.

Any ideas? Thanks.

[alabbasi]

White smoke would indicate water mixing with the gas. This is another D-Jet car. Have you done a compression test on it?

I would start there.Then clean the plugs and drain the oil and put new oil in place as you may have gas in the oil.

The come back and tell us what it's doing.