1999 Mitsubishi Chariot Runs badly when in gear.

Car runs fine when idling - can rev and relase with no pinging/knocking or backfiring, have cleaned the Throttle body today as it was smoking a bit much and I thought this may improve my current problem, which it hasnt.
Issue:
When you put the car in gear (forward or reverse) it sputters and has limited power - similar to how an old car with the choke out behaves, keen to understand what causes this type of behaviour