So the story goes that I was driving down a road thats got some construction going on, after getting half way down the bump road my cat starts to make this horrible helicopter-like noise. car developes major problems, no longer really drivable.

So blah-dee-blah I get a catco highflow and get it installed, the old was was completely clogged, car runs much much better. but its still not right.

it doesnt like to go over about 4k RPMs, nor does it like to be at ~1200 rpms, it shutters really bad if I keep the throttle at about 1200, the dash shakes and all that fun stuff. It doesnt like to be floored, it kinda chugs when you floor it.

Also, not sure if this is relevent to my problems, but there is a odd "tick-tick-tick-tick" coming from the pully with the crank sensor, the ticking goes with engine speed.

Could this be a spark problem? a fuel problem? a timing problem? Im sorta lost here on what it could be, and what to do about it...

Thanks for any help you guys can give me.

DK

Well, the good part throttle performance and the bad full throttle performance is consistent with that of excessive exhaust back-pressure. This can really only be caused by the cat or crushed tubing. Since you replaced the cat, maybe it was installed wrong? or perhaps defective? or some exhaust tubing is a little bent up.

If neither of these seem plausible, an exhaust back pressure test may be in order. This is extremely simple to do, but you need a back pressure [may also be built in to a vacuum gaugie too] gauge, and the associated fittings to connect it into the o2 sensor bung.

Could also be quite a few other things, but exhaust first comes to mind. Whenw as the last tune up on the car anyways?