Any number of things can cause your car to run poorly.

How are your spark plugs, wires, distributor, coil, distributor cap, etc. Are you using premium fuel?

I had a car that ran less than optimally on regular. Ran better on premium.
A misfire would go away when I used premium.
One of my plug wires was loose. Problem solved.

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'O=00=O'
bmw 2002.
long live the legend