car surges at 50mph uphill?

[Nathan300]

Hello,

I am new to this board, I was directed here by another forum and I am hoping someone can shed some light on a problem my father is having with his car. He recently bought a 1995 525i with about 130,000 miles on it. It only has one problem, when traveling right about 50mph (and so far only when going uphill) the tachometer starts surging back and forth about 500rpm. This is our first BMW and we are not quite sure what is causing this. My father thought it might be the oxygen sensor so he had it looked at and the mechanic found it to be malfunctioning. Yet after replacing it the problem remains?

Any thoughts would be appreciated

thanks

[bjl4776]

The back and forth im not sure about, i have a 92 525i 5-speed, and it started surging uphill, or when i give it gas, shortly after that i had to replace the clutch, but it doesnt quit sound like the same thing, maybe its the automatic equivalent, not to familiar with autos, try to stay away from them.