engine hesitating

[Karl Robrock <robrock@domain.elided>]

I am experiencing a problem during acceleration in my 164L. It seems that
in first gear the engine lacks power and shakes until about 3000 rpms.
Above 3000, it runs beautifully, and regains power. In other gears such as
4th and 5th, while drifting or maintaining constant velocity it is fine,
but if I accelerate, even above 3000 it shaked (not too violently, but
noticeable). Also (I have trouble describing this), the exhaust system
sounds like a harley, in that it emits a very low frequency (~6Hz) berp. I
don't think it has always sounded that way, although I don't generally
stand right next to my exhaust pipe.

The hesitation I thought might have been due to a clogged fuel filter or a
defective fuel pump. I did run out of gas once, becuase I underestimated
the gas consumption at 110 mph. Fortunately I was a block from home.
Another time, I let the car sit in cold weather with a mostly empty tank,
which could have caused the formation of water in the tank. I put dry gas
in before driving the car again.
I also seem to be getting poor gas mileage although not positive. that
might be due to the snow.

if anyone has any suggestions, please let me know.
thanks,

karl
'91 164L

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