trouble putting throttle body back on

I'm brand new to the list so . . . Hi

I just bought a new 4 cyl 95 metro Lsi about 3 wks ago. It runs great but cuts out at speed. I won't get into that whole mess (yet) but what I need to know is this. I removed the throttle body so I could put a spare one on that I had cleaned up really good in hopes this might help. But when I put the throttle body on, the throttle lever wouldn't go all the way back into place or even get very close to the stop screw. This makes the rpm's shoot through the roof when I start it. I tried to take the tps off and manipulate it with the car running but it had no effect. It seems like (excuse my ignorance) the big black box on the back of the throttle body that has a plunger is getting in the way and not allowing the throttle lever to go all the way back to the stop screw. I've looked at another metro to see if I put something back together wrong and I don't see any difference, other than his throttle lever goes almost all the way back to the stop screw. I put the original throttle body back on the car and I have the same trouble.

The car runs great and I'd like to get it to a mechanic but I can't drive it anyplace because it is revved so high. I'd probably kill something if I tried to throw it into gear.

Thanks so much for any ideas or responses.

Chad