1992 Acura Integra GS review from North America

After doing much research on "reliable" used cars, I bought my 1992 Integra gs with 120,000 miles on it, and after one month of driving it it started having problems. On the highway mostly, the rpm's would drastically start to jump anywhere from 2,000 to 6,000 within seconds on a random basis. Sometimes while driving, the car would just shut off and then turn back on seconds later. I know very little about cars, but it felt to me like the gas was somehow not getting to the engine. Other times when it would shut off, I had to pull over and wait about 15 minutes until it decided to start back up again. This happened more frequently the more I drove it until eventually it wouldn't start up at all.

I had to let the car sit for 6 months until I could afford to take it to get fixed. When I eventually did they replaced the fuel filter, spark plugs, plug wires, distributor cap, rotor button, and cleaned the fuel system as well as an oil change which came to $389 and was supposed to fix the problem. Well I just got it back from the shop yesterday, and when I took it on the highway the rpm's still did a little jumping and the check oil light came on. This is how it all started in the first place until it eventually got worse and worse to where I couldn't drive it. Now I wish I never bought it in the first place.

Can anybody tell me why this might be happening?

This car is fun to drive when it is working properly.