Hello,

I have a '91 CRX HF, with a used motor with 99k on it, installed this November. The car itself has over 220k on it now. It ran great when i first got it put in, but recently the last few days, i will be driving it down the road at a steady rate of speed, with my foot lightly on the gas (RPM's between 2.5k -3k), and it will start to jerk a little, maybe misfiring a little or something. When i press down hard on the gas, it usually regains, but it's starting to do it a little more now.
Any ideas? Today, i changed the fuel filter, spark plugs, spark plug wires, added some fuel system cleaner, some more gas, and it is still doing it.
Personally, i'm wondering if it could be the distributor cap. Maybe the fuel pump? When we took out the fuel filter today, my friend said it was pretty old and dirty, probably came stock with the car 16 years ago. Perhaps the gas tank is filthy inside as well, and could need some sort of cleaning. Some help from anyone on here would be greatly appreciated.

Thanks.