help!

hey guys i got a 94 v-6 stang and idk what happened with it. about a week ago i came home from my trip from florida, i took my car out the night i came back and it ran perfect. the following day i drove it to school it seemed fine but i cant really remember, but on the way home i realized that somethign was wrong, it was very sluggish until about 2 grand. so i was kinda skeptical about it, but didnt really think it was anything major the next day i noticed it got worse and i had to almost ride the clutch a little to get it moving, i didnt use it the rest of the day and the next day when i wanted to see what was wrong with it i noticed i had to rev up to about 3 grand to even get it moving, it was so sluggish gettin up to about 20 took forever. i changed the spark plug wires thinking that it may be part of the problem and after, my car could barely start. i also noticed the first day the problem started, this is what kinda gave me the idea something was wrong was when the cltuh was in or basically just idleing the car normaly ran about 700 rpms and it was only about 500 now and almost stalls. i brought it to my local mechanic and had him look at it. hes had it for about 2 days, replaced the spark plugs, the wires, thought it may be a problem with my catalytic converter gettin clogged, thingsl ike that, but has yet to find the problem.. i have no idea what is wrong with it when you wanna go forward, the car now basically stalls. anyone know what could be wrong with it???
thanks for reading...if anyone knows please let me know!

Have Your Mechanic Check Both Fuel Filters. The One Inside The Tank Got Cloged Up On Mine And Had Simaliar Probs. But The Mechanics Never Think About That Till Last. I'm Surprised He Thought Of The Cats (good Guy) Most Dont Think About That That Unless Its Real Old. Good Luck