Mechanical problems

I have a 95 golf III w/ 113k miles on it. I have a problem with a few things. I have a constant rev when i'm shifting through gears. (ex: off accel. onto clutch, engine revs, shift gear, and accel again.) its does this none stop. I thought is was the oxygen sensor so i had a new one put in along w/ a new exhaust. turns out that wasnt the prob. No i hear it might be the idle stabilizer. Other problems i have are when im idle and accel, the engine will lock at 1000rpm, u can push the accel. down, but will get no power for a good 2-4 sec. My last problem is when i will be driving in any gear: 2nd, 3rd, 4th, 5th, etc. and all of the sudden my car will shake rediculously. no matter what gear, no matter what speed this happens. Now the stange thing is, is that it only does it sometimes, but this can be annoying esp if u have some chicky in the car with you, LOL. I've read that this could be an ignitions coil problem. possibly spark plug???? well if anyone know about these problems or know of ways of fixing them please respond. thanx.