2004 Chrysler PT Cruiser RPMs

I'm a struggling 54 year old single woman who is trying to start a career after just graduating from the master's program. I barely have enough money to pay bills. I've been taken advantage of. My car will start and if the rpms won't rev above 2 1/2 it will not run for me. I have to turn it off and sit and try again and eventually I can rev them up over 2 1/2 and it will drive for a while and then the rpms will dive and the car will buck and I have to repeat process of turning it off and sitting. I took it to a mechanic who kept it, couldn't tell me what was wrong and charged me 200.00 to get it. They did no work on it. Now it is in OKC at another mechanic place and he will charge me 50.00 to look at it. I just now have been able to buy property and starting to get on my feet. Have a job, but all money goes to bills. I will have to pay it out if he will let me. Please help me know what my mechanical problem is.