Well, my first thought is that you probably have a bad Throttle Position Senser, not just dirty contacts.
Beyond that, check your plug wires, ESPECIALLY the coil wire. I once had a car that had the exact same symptoms you speak of. Back then there were no scan tools available to me. I checked the plug wires and they seemed fine, so I assumed the fuel injector. After replacing it I has the same issue.
Upon further investigation I found that the COIL wire was shot. Literally an inch of it was powder! Only when the engine was revved was enough voltage generated to jump the powder and make the engine run closer to normal.
Don't know if that's the issue in your case, but it's worth checking.