HELP! HOW CAN I FIX MY 1994 PLYMOUTH VOYAGER! NEED TO GET MY KIDS TOO DOCTO?

HI, I OWN A 1994 PLYMOUTH VOYAGER, 3.O LE, 6 CYLINDER. THE EXHAUST ROTTED, & SEPARATED FROM THE ENGINE(MANIFOLD). THE MUFFLER ROTTED OFF ASWELL SO I TEMPORARILY PUT A PIECE OF FLEXI PIPE IN ITS PLACE. I DROVE THE VAN(VERY CAREFULLY) TO A GARAGE 4 MILES AWAY TO HAVE THEM RE-CONNECT THE EXHAUST TO THE ENGINE. THEY GOT THE PARTS, & DID THAT($100)...WHEN I LEFT THE GARAGE I NOTICED A HESITATION WHILE TAKING OFF IN THE DRIVE GEAR, THEN REALIZED I HAD NO POWER GETTING UP HILLS, THE ENGINE WOULD BUCK, BUCK, BUCK & THEN STALL. HOWEVER, IT HAD POWER IN REVERSE, & WOULD GO UP HILLS OR WHEREVER IN REVERSE.
I BROUGHT THE VAN TO A TRANSMISSION SPECIALIST WHO SAID I WAS MISSING A COUPLE ENGINE BOLTS(PROBABLY FROM THE BUCKING), & THAT HE CHECKED THE FLUID, & TRANSMISSION & THAT LOOKED FINE. HE RAN A COMPUTER TEST, & SUPPOSEDLY GOT A CODE FOR A OPTICAL SENSOR PROBLEM. HE SAID HE WOULD LOOK AT IT AGAIN THE NEXT DAY, & MY VAN SAT THERE FOR 6 DAYS, & HE NEVER LOOKED AT IT AGAIN. I WENT TO HIS GARAGE PAID HIM WHAT I OWED HIM($75), & DROVE MY VAN BACK HOME(1 MILE). ON MY WAY HOME I NOTICED THAT THE VAN WAS SMOKING OUT OF THE EXHAUST!!! I CALLED THE MACHANIC, & HE SAID THAT THIS MAKE IS NOTORIOUS FOR THAT, & IT WAS NORMAL!!!
WELL RUNNING LOW ON CASH I CALLED A FRIEND, HE LOOKED AT IT, & SAID THAT IT SEEMED AS IF THE CONVERTER WAS CLOGGED, & IT NEEDED THE MUFFLER. I BOUGHT THE MUFFLER ($89.99)... HE KNOCKED OUT THE FILTER IN THE CONVERTER, & PUT ON THE MUFFLER. NOW, ALOT QUIETER THAN IT WAS IT STILL LOST POWER, & DID THE SAME THING IN DRIVE...
MY FRIEND DECIDED TO CHANGE THE PLUGS, WIRES, & DID A FUEL PRESSURE CHECK WITH THE KEY ON. HE THEN CHANGED THE FUEL FILTER, THE OXYGEN SENSOR, THE COIL, THE DISTRIBUTOR CAP, ROTOR, & FINALLY THE OPTICAL SENSOR IN THE DISTRIBUTOR. WELL NEEDLESS TO SAY THE VAN STILL DOES THE SAME THING BUCK, BUCK, WHEN TRYING TO ACCELERATE UPHILL IN DRIVE, BUT IT STILL GOES IN REVERSE LIKE NORMAL. EXHAUST IS SMOKING A LITTLE WORSE.
PLEASE HELP ME I NEED MY VAN TO GET TO WORK, DOCTOR APTS. FOR MY KIDS, & FOR EMERGENCIES. I HAVE SPENT MY ENTIRE SAVINGS, & I REALLY NEED HELP ON THIS...

THANK YOU SOOOO MUCH!!!