2002 Millenia P - RPM fluctuation, hesitation and surge, P0300 multiple misfire codes

I have a 2002 Mazda Millenia, 2.5 l. I am getting engine rpm fluctuations of 500-600 rpm, even after popping transmission into neutral and trying to hold rpm at ~ 1700.
At other times, I get a very short, single hard jerking motion. Occasionally, the sets the multiple misfire trouble code. Reset trouble codes and same one returns, but maybe not for some days. When engine/transmission are not hesitating, which is only occasionally, all runs just fine.

Odd behavior in that engine MIL will come on for some miles, then go out again. Its as if the ECU is losing power intermittently.

I have a bluetooth scantool and PC diagnostics from TouchScan (obdsoftware.net). What should I be looking for? Several recordings show no obvious problems in O2 or fuel trim sensors.

hello,

make the throttle clean if it doesnt work, make the idle controller clean. Or maybe you have just not enough coolant/cooling liquid.... but it can also the throttle position sensor be. Check it

Vacuum leak!!! Finally found a hose that had come off bottom of intake tube/ air box.