2004 Forester XS 5-speed
500 miles on new oil and filter
500 miles on new K&N air filter
Rough idle was cured with seafoam approximately 2000 miles ago
My car has always run great and has given me no problems in the year I've owned it. I've put a lot of miles on (20,000+) but I have kept up with the maintenance religiously. It did start idling a little rough a few months ago and I gave it a full seafoam treatment last month (2000 miles ago). That is the only thing I have done out of the ordinary and everything has been kosher since.
This past week I got an oil change and installed a new air filter then drove 500ish miles from Pennsylvania to Vermont without incident. When I left Vermont to come home, I got about 30 miles down the road and the car started stuttering and hesistating when I'd get on the throttle hard. I figured, it might be a fuel filter so I picked one up and AutoZone and swapped it in the parking lot. I also put a bottle of seafoam in the fuel tank in case I had a gunky injector.
Even after swapping the filter, the problem persists. It idles great and runs totally fine at any RPM, but if the engine gets under too much load, like accelerating or maintaining speed up a hill, it starts stuttering and cutting in and out. It hasn't stalled yet, despite me going pretty hard on it a few times just to see what would happen.
It runs well enough that I made the 500+ mile drive home just fine, it was just annoying to pass people or go up big hills.
Anyone have any idea what's going on? I am completely at a loss and would love some advice.
Edited by jmoss5723, 08 July 2013 - 02:03 PM.