Chevrolet Repair: 1989 chevy Camaro won go over 20mph, chevy camero, clogged catalytic converter

Question
My nephew bought a 1989 chevy camero in Oregon this summer and drove it back to Indiana about a month ago. He says that it has never shifted gears very smoothly, but he assumed it was because the engine was replaced with a rebuilt 360 block and the the transmission was still the old RS stock. Yesterday he drove it to work, but when he left to go home it wouldn't accelerate over 20mph. I already had him smell the cabin of the car while it was running to see if it may be going into vapor-lock from a clogged catalytic converter and he's pretty sure that there is no catalytic converter on it, just straight pipe.

Answer
HI VANESSA,THIS TO ME SOUNDS LIKE A PARTIALLY PLUGGED EXHAUST SYSTEM OR THE TIMING JUMPED OR PLUGGED FUEL FILTER...HE WILL NEED TO JACK THIS CAR UP AND MAKE SURE THERE IS NO CONVERTOR IN THE EXH..IF THERE IS THERE IS A VACUUM TEST TO CK FOR PLUGGED EXH..HOOK THE VACUUM GAUGE UP AND CK THE READING SHOULD BE AROUND 18 TO 20 INCHES OF VACUUM AT IDLE, THEN RAISE THE IDLE UP TO 1500 RPM'S AND THE VACUUM SHOULD DROP BUT COME BACK UP TO AROUND THE SAME AT IDLE..IF LOWER THEN THAT THEN THE EXH IS PLUGGED. [SOMETIMES] THEY THE CAT WILL NOT SMELL. THE OTHER WAY TO CK IS TO REMOVE A OXYGEN SENSOR FROM THE FRONT EXH PIPE BEFORE THE CAT AND DRIVE IT LIKE THIS [IT WILL BE LOUD] BUT IF IT RUNS BETTER WITH MORE PEP,THE EXH AGAIN IS PLUGGED...IF THERE IS NO CHANGE WITH THE ABOVE TESTS GET THE ENG UP TO TDC  AND REMOVE THE DIST CAP AND CK TO SEE IF THE ROTOR IS POINTING AT NUMBER ONE ON THE DIST-CAP..NUMBER ONE CYLINDER IS THE FRONT ON THE DRIVERS SIDE FOR A V8 CHEVY ENG,IF WAY OFF TURN THE ENG ONE TURN TILL THE ROTOR IS AROUND THE NUMBER ONE ON THE CAP. THIS WILL BE TDC COMPRESSION STROKE..THIS SHOULD BE VERY CLOSE IF NOT THE CHAIN MAY HAVE JUMPED. IF YOU DO GET BACK TO ME LET ME KNOW HOW THE ENG RUNS AT IDLE AND OFF IDLE,IF IT RUNS SMOOTH THIS SOUNDS LIKE WHAT I MENTIONED ABOVE..IF NOT MAY HAVE IGN PROBLEMS. LET ME KNOW HOW THE ABOVE WORKS OUT FOR YOU AND GET BACK TO ME..GOOD LUCK TO YOU,,,TOM...