I'm not sure if anyone has or has had this problem, but I received help for this problem and just wanted everyone to know the outcome... I have a 1993 Honda Prelude Si.

The Problem: When the gas pedal is pushed down lightly for normal around town driving the car was cutting in and out and like sputtering a bit. Once the gas was pushed about half throttle everything was fine (obviously not a timing issue... THANK GOD!) My first thoughts, were fuel delivery, ignition, or something was messed up in the head or block... after running a compression check and showing 220 psi all the way across I knocked out one possiblity (the most expensive one)... then I replaced the plugs, wires, distributor, and tested the alternator. None of those were it. I got mad at the sputtering and down shifted from 5th to 3rd at 65 mph and power shifted the next 2 gears... when I went to pull away from the next stop light, the exhaust was unbelieveably loud and obnoxious. I thought I blew the exhaust manifold gasket (well, the pacesetter headers gasket lol) but anyway, come to find out two welds on the downpipe blew out... reason being the catylitic converter is the stock one (car has 207,000 miles on it) and all of the guts have been breaking down over time lately and discharging into the stock muffler... there was just so much back pressure that the exhaust when the throttle was only a little ways down would come back up into the engine and [freak]ing w/ it. I'm fixing the welds, getting a performance cat, eliminating the resonator, increasing the diameter of ALL of the tubing (except the downpipe) just by a little for a little extra breathing room, and ending it w/ a nice polished skunk 2 4.5" outlet (fart can lol)... i'll take pictures and post them where appropriate. thanks for all the help guys!

 

thats funny u have that prob. i have a simular prob. but i dont have a cat.