[ImperialCrown]

If no codes, I would check the secondary ignition system first. The distributor cap button should have a shiny spot where it contacts the rotor. The inside of the distributor should be free of 'dust'.
The plug wires should be pushed fully into the cap and be a recent, quality brand.
The spark plugs should be the OEM Champion Copper+ RN12YC.
How do the tips look on the current plugs? Carbon or white?

Is the kickdown cable return spring there and able to return the cable to 'idle'? Is the throttle lever slot that the cable slides in free of corrosion and allows the cable to slide in the slot (with return spring pulling it back to the 'idle' position)?
If the throttle (kickdown) linkage if free and not binding, then check for proper cable adjustment.
The horseshoe retainer at the bell-housing should pry and pop up, the cable should seek its own 'center', then secure the horseshoe back down to hold the adjustment.