1992 Mazda 929 Engine seems to misfire, rough ignition

1. Car engine “misses” and lacks power. This occurs on level pavement as well as on hills. Sometimes it seems worst when turning an uphill corner in either direction and trying to accelerate. This is an intermittent problem is not always evident in a test drive. It is as though the engine is not getting enough fuel – it’s “chugging”. More recently, engine idles roughly even when not moving but in gear.
2. Check Engine light came on, November 2, then it went off again. It is not lighted now. The timing belt was replaced at 112,800 miles. Electrical systems have been evaluated – distributor cap & rotor were replaced at 119,793 miles.