95 jetta bucking and hesitating

this is a big pain in the ___:banghead: i have researched, asked people and no one knows what the problem is. i jus went through the car checking everything, spark plugs, rotor button, cap etc.... the car has to turn over a few times in order to ( fire ) i guess and idle jumps between 1000 and 0 almost cutting off before i tap the gas, once it starts it runs fine on the highway or atleast as far as i trust to drive it, but 20 or 30 mins city driving it starts to jerk and eventually bucking like a mule. shut it down for a few mins and fine for 10 to 20 mins before starting back up.. this happens hot / cold dry or wet weather i think it is the coil not sure, if anyone can help narrow this problem down would really b gratful. i'm on a really tight budget can't sink alot of money into buying parts i cant return or dont need Thanks for any input