92 camaro problems!! need help!

i have a 92 camaro rs v8, it worked great when i got it but now it seems like it doesnt have any horsepower. When i press the gas, it doesnt go like its supposed to! Somedays it will only go like 10 mph and when i hit the gas it just chokes out and i have to restart it like 3 times to get it to go fast enough.
i have took it to almost everyone i know and they cant seem to find out whats wrong with it, so i need some help really bad!

Maybe it needs. A tune up