My first question on this forum!

I have a 1997 E300D with 72K on it. I am the third owner as of December 2004. I have driven it for 12K miles. When I bought the car I had both fuel filters changed and the air filter. I also changed the oil. The pre-purchase check revealed no codes in the computer for any engine problems. This car was purchased in Conn and was driven there prior to my purchase via a dealer / MB auction in PA. It was Star-marked at 38K. The miles check out via Carfax.

Here is the problem. When I cold-crank the car and drive for the first 3 or so miles I typically get a "skip or studder" for maybe 4-5 times in one burst prior to normal operating temperature or a single 1/4 second skip once before I attain operating temperature. At times I get a single skip at highway speed when the engine is warmed up.

Since I am a diesel driver for over 20 years (and own a very nice 1987 300D for 7 years now) I thought well maybe it is the fuel tank....I added Red Line Diesel fuel catalyst - one bottle per tank and I get no skips for the most part for the first 1 - 1.5 tanks of fuel. My fuel mileage jumps 3-5 MPG and once I discontinue use, the problem comes back. Problem is this stuff is $4.99 a bottle so I don't want to use it all the time and I wonder what the stuff might do to the engine over time anyway.

Any ideas anyone? I don't want to throw a bunch of $ at this car trying to figure this out....

Thanks!