I recently purchased an 03 evo that I'm very pleased with. It has a little over 41000 miles on it but it's in excellent condition. The person who had it before me installed an hks intake, a grounding kit, a helix high flow cat, and a full 3" cat-back exhaust system though I'm not sure what brand. I recently had an (ses) light come on so I extended the O2 sensor back with that spark plug fouler trick I read about on here. I took the car for a drive that same day and everything seemed fine. I ended up giving my evo the week off and took my 350z to work. When the weekend came around I took the evo for a drive and it seemed to be lagging big time. I accelerate and the rpms seem to jump really high then chug back down then back up. The whole time I hear the blow off blow just sort of releasing pressure. It drives smoothly at any certain speed but as soon as I accelerate it does the same thing. It revs like hell for a sec then calms down then accelerates again. Has anyone experienced this. A friend of mine tells me it could be the blow off valve. As far as I know I technically still have powertrain warranty though I'm wondering if any of these parts will void it?

 

A BOV would not cause such symptoms. This sounds like a classic slipping clutch. To test this theory, go out and drive in 5th gear at low speeds and floor it. The moment your boost starts to build, if the rpms quickly jump up without you accelerating much, then drop back down and catch, you probably have a slipping clutch.

This would not be covered by any warranty, nor would anything on your car, since it's at 41k miles and previously owned. You don't get the full, original warranty as the 2nd owner.

 

Thanks for your help...I called the local mitsubishi dealership and they said that it would be roughly around 1300 to 1400 dollars to fix. So I figure I'd be better off buying an aftermarket clutch. Not sure what kind to get though.