please help 1997 VW jetta gl is broken....

i have a 1997 VW jetta GL 2.0 with 150xxx miles. i bought it a couple months ago and it slips out of reverse and makes a grinding sound. but i made due and just avoid rev. that was the only problem. that is until last week i took it to jiffy lube. they replaced the oil, oil filter, air filter, fuel filter and flush/fill the transmission fluid. i drove it about 80 miles and it became nearly unresponsive when i would switch gears and try to speed up. i barely putted into work. now i can start it up but it idles weird and if i gas it will either lag and almost die then shoot up rpm to 3500 or just die. any ideas?