97 protege rpms fluctuating

When I am driving every once in a while the rpms' will start going up and down. Almost seems like a fuel problem but not sure. Also having a random misfire on cyclinder 4 of the engine. Maybe it has something to do with that who knows.... Have replaced distributor/wires/ plugs(over 600 job) :frown:

For the engine misfire: Have you replaced the valve cover gasket. They tend to leak (if really old) into the pit that the spark plug is hidden in and causes it to misfire.
Idle: Clean your idle stabilizer valve, it's integrated with the throttle body on the back side if I remember correctly.

we changed the valve cover gasket a few months ago. also checked the entire ignition system. the car just seems to be bogging down until you get to about 3200 rpms... then it picks up and seems fine and has more power.... i may think it might be a egr problem i hear protege's have problems out of those too... a

Have you done a compression test on the cyclinders ? A cyclinder with low compression can also cause a missfire.

The egr sounds like a possibility. Check your mass air flow sensor and for vacuum leaks. Do the RPM's fluctuate at idle or when running?