Impul-R33

all gears,but not in neutral, it would make sense it being the fuel filter or fuel pump, its been sitting for a while, my manuel is in japanese so maybe you can help me out on this one, Where is the fuel filter? the only one i ever replaced was in the tank and i could gain access to it thru the trunk, I'm guessing its an inline filter under the hood to the left of the intake manifold but i cant tell, it could also be a regulator of some sort.

the ecu, i have no idea, it was originally tweaked by impul, then tweaked again by a german tuning company called RAZO, right now its running 105 US octane rating

full stock,about 5 psi the only aftermarket is a downpipe back jasma exhaust and a tune job RAZO(who knows) After 4700 rpm anything more than a granny foot the car starts stuttering

I am a soldier in the US Army and i have been stationed in landstuhl, germany. I bought a 1994 Skyline GTS-T Impul edition sedan from an older local german. The problem the car is having is when the revs reach 4700rpm under acceration (autobahn ) the car feels like it hits a wall, like rev limiter, but if i ease off and accerate slowly with no boost it will break through the 4700 rpm mark just fine. It seems to me the only time it hits that wall is under moderate acceleration when boost is up. The things on my list to do are ngk plugs, fuel filter, and spaying the mass air flow meter with some brake cleaner. I've ran a tank of fuel with stp fuel injecter cleaner through it since i knew it had been sitting for 6 months but what else should i do? How can i accerlate moderately without hitting that wall at 4700 rpm?