1984 300D -- Low Power at lower speeds

[Paul Divin]

I have a 1984 300D Turbo. A week ago I was asked to test drive a non-turbo 300D and found it had a lot more power than my 300D Trubo at lower speeds.

I was shocked. And spent weekend in the mountains with overnight temperature at about 22ºF. The car started OK. I let it warm up for about 5 - 10 minutes. When I drove it, I could hardly get it to go more than 10mph. It is a little better with overnight temps around 50ºF.

It has new fuel filters (both) and air filter. Valves have been adjusted recently. Oil changed. I never use bio-D or VO. It always starts easily. When it stops, there's a little hesitation. But that is the vacuum, not lack of compression. As soon as the vacuum kicks in, the engine stops immediately. I drove at 55mph for 3 hours and got 38mpg. I have never gone over 100mph, but I think it would easily do it. It's a clean machine and sounds good too.

Once warmed up and at higher speeds it has a lot of pick-up. Perhaps jelling was a problem overnight at 25ºF. But I don't think the fuel is jelling with evenings at home at 45ºF and above.

Could some vacuum thingy be affecting it? I get whistling noise when the climate control is set at "closed" (O). As soon as I change it to the normal AC position it stops. The noise happens as I lay off the acelerator after increasing speed.

So why is this thing a dog at lower speeds?

Thank you,
Paul