Chasing an intermittent low speed stumble: 1992 b230f with Regina in pretty nice unmolested condition, some 200k miles. Starts up, idles, revs up, all good! After a few minutes and warmed up on the road, will stumble, choke, from stop, and at low speed, all this happens sometimes, not always, unrelated to anything I can pinpoint. Revs up great in Park, no sign of stumble there. Under full power, acceleration, highway driving, etc. all is great--no sign of the stumble. The "tune up" parts, plugs, cap, rotor, wires, CPS, O2 sensor, all good and recent and OEM. Ideas re similar woes very much appreciated!