now i think that its an exhaust leak on the tercel not the cat cuz when i turn it off it kinda sighs... so i think thats the exhaust (or my car being so depressed its so slow)
if u can get ur car on a hoist....u will be able to see or hear where the exhaust is originating from......an exhaust leak is simply a hole in the exhaust....could be from rust...or from a broken flange....