hey ive got an auto 04 lancer es and when im going 45+ you all know how it changes gears. well if im almost wot, it will shift where it is supposed to, but it sorta hickups/stutters. now i have an axleback exhaust, and with the louder muffler i can hear it. and i was wondering if anybody knows abt this. it will get up to 4-5k rpms and it'll rev, make the sound like its shifting, then rev higher again. and i mean im not pushing harder on the throttle, nor am i letting off. is this bad? help please! and thanks.

 

check your tranny fluid.

 

how often do u need to change it? b/c we we're supposed to do the 30k checkup, 4k+ miles ago.but oil changes should be up to date.