engine surging

The vehicle is a 1989 Suzuki sidekick with a 1.6 tfi w/ an automatic jlx 4x4. The engine would not run without pumping the throttle constantly. Replaced throttle poisition sensor, with no luck. Found a used throttle body, installed it. fixed the original problem now the engine surges between 800-1500rpm while in park only (when in gear it runs very smooth).setup tps per manual instructions, but still no luck. when you look into tfi you can see the fuel spray then pause. ???????????????

Did you ever find a solution to this problem? I have a 1991 sidekick that is doing the same thing.