Ok, fc seems to do fine cruising through main roads and what not but when i get on the highway and put it into 5th gear it's like the car wont accelerate. If i leave it in fourth i'm fine. I've also noticed a vibration at that speed when in fifth gear, dont know if it might be related?

 

How fast are you going when you go into 5th? It's not really an acceleration gear...

 

generally i'll drop the car into fifth around 60-65 mph on the highway, after that it just lulls, i've owned two FC's prior to this and never had this problem.

 

What FC's have you owned. The gearing is different on the GTUs.

 

I have this problem, but then again i live in CO...

 

I vote for clogged exhaust, dirty fuel injectors, TPS out of spec, or intake system problems (6th ports, VDI, 2nd throttle plates).

 

Depends on the RPM. Anything below 2500ish and it will shake the **** out of the car and you won't go ANYWHERE.

 

Wouldn't that all affect any gear, not just 5th?

 

5th isn't meant for acceleration, it's a fuel economy gear. When you need to accelerate, shift into 4th.

 

A general overall power loss will be most noticeable in 5th gear crusing. With a clogged exhaust I especially noticed this on a friends car (his automatic rx-7 convertible ran rings around his manual coupe). I kept having to downshift to 4th because it had no / negative power in 5th.

 

Think it may be the intake.....pulled it today and it didnt look so hot, going to try and replace the filter and see if that solves my problem. The exhaust is fine though, i recently had a racing beat header and 2.5' piping installed, purrs like a kitten

 

Well thankyou to all who helped with my prob. I was inspecting the engine and looking over a few things when i noticed my spark plugs were VERY loose. The guy who built my motor put them in so loose that i could pull each one out with my fingers. After tightening them in it was like a world of difference. Thankx everyone!