Jims 92 lt1

I have an intermitten performance problem. Automatic transmission. This only happens at speeds between 45-60 at about 1000 -1100 rpm. When you try to accellerate car stumbles and: shakes violently as if starved for fuel or air. Car is averaging 19.5 mpg. has no stalling issues and generally runs great. Never any hesitation from a dead start, no slippage from the transmission and only seems to happen on the highway at low rpm in 4th gear. The problem goes away for a week and then comes back. Has a new opti, rebuilt inj from frc .( checked ohms all the same.) Any ideas would be appreciated thanks jim

AQUILA163

Did you change the plugs and wires with the opti? If you have a bad wire or bad connection it may be missfiring or worse cross firing in the cap. The conditions you discribe are the time when the most resistance exists across the spark plug gap and high resistance in the secondary ignition will be exposed.