I have bought it up before and here's the link for the problem

 

http://www.ultimatesubaru.org/forum/showthread.php?t=94359

 

I am wondering if a clogged cat will allows my car rev to 5k. A friend of mine helped me to diagnose the car and he rev the car to 5k and everything seems fine. Only when it's in gear it will do the hiccup thing... I'm really puzzled. I have changed the fuel filter and pcv valve with no avail.

 

Thank you all!

 

Vincent

Is the check engine light still on? If so, do you know how to read the codes? We need to find out what they are.

here it is

 

http://www.ultimatesubaru.org/forum/showthread.php?t=95778

Is the exhaust flowing out like it should be or does it seem like it is restricted? Others have had this same kind of trouble I think and found the MAF sensor to be the cause of it. Cleaning it may help solve the trouble. A dirty throttle position sensor may possibly cause this trouble also.