Plymouth Neon "check engine light" problem

I have a 1995 Plymouth Neon. It has a standard transmission, I believe a 4cyl engine, and about 58,000 miles. The "check engine light" appeared about a month ago with no noticable problems. I had the oil and air filter changed and added a bottle of STP fuel injector cleaner to the gas tank. This did not help and soon after the car started to loose power between 3rd/4th gear. If I pumped the gas pedal or held it to the floor, it would hesitate, backfire and then surge forward. Today however when it started to loose power it would not regain it until I pulled over several times and started off again in 1st gear. When I finally made it home there was a strong burning smell for a few minutes. I know it needs to be fixed but I am a middle aged woman who is at the mercy of any repair shop that could tell me anything and I'd be none the wiser. I can't afford a large repair bill and need some help as to what could possibly be wrong. Please help me if you can.
Thank you very much.