85 crx si coughing/sputtering

My 1985 CRX Si starts immediately, runs smoothly for 3-4 minutes and then begins to go into some "auto-rev" symptom. After several minutes, that stops, everything is normal. Recently, I have noticed sluggishness whenever it rains, or high humidity (The O2 sensor light does not come on and that sensor was replaced over a year ago.). Timing belt was replaced 8,000 miles ago. Now the car seems to idle as if it is starving for fuel and hesitates and misses as I feather the foot feed to achieve enough RPM to keep the motor running. If unsuccessful, the engine dies and a backfire is heard but no starting. Sometimes, the car will start with the pedal floored and some feathering of the pedal while the engine is trying to start with the aid of the starter kicking it along. If the car sits for an hour, or so, everything is back to normal. No backfire, starts right up. In fact, it starts at the very flick of the ignition key...not even taking a second to fire up. Any idea what it is?

:wave:Welcome to AF. I can't help you but try the crx board.