This problem occurred a few months ago fixed the first time but problem came back. The idle is normal and full throttle is good but when i have 25% or less throttle while crusing the car acts like a misfire/ hesitate. I've replaced plugs wires distributor assembly fuel filter iacv.

 

had similar issue on my b20. cleaned IACV, cleaned and "reset" the fast idle valve, and put a new throttle body gasket on. It was all REALLY dirty and gasket was garbage. Worked for me.

 

Dont have a fast idle valve and tb has been cleaned and new gaskets but no luck

 

I'm assuming CEL is not on (and CEL works) so there are no codes. If there are codes, don't expect car to run properly until they are resolved.

Check the TPS (throttle position sensor) with a voltmeter, with the key on but engine NOT running. Measure from the center wire to ground. Should be 0.4 volts with the throttle at idle, and increase smoothly as you open the throttle. If there are jumps and gaps in the response, it is worn out and needs replaced.