i have a 2001 f4i 13000 miles. to start things off i have recently replaced FPR (i had 90+ psi of fuel,but that problems fixed), the spark plugs are new, fuel filter replaced, gas tank is clean, air filter clean,i have a short exhaust on it (other than that its all factory),firing on all 4 cylinders, NO fi light, THE PROBLEM: the engine just does not feel as smooth as i think it should, idle is a little "gurgly" and fluctuates a little.Just doesn't feel right especially compared to my buddys 06 f4i. from everything i have been researching i thought the problem might be in the starter valves on the throttle bodies so i decided to take a stab at it... i built a homemade "manometer" that everyone was saying to do and i also hooked up regular vacuum gauge to them as well and i can not get them to balance, i hooked up to the correct vacuum hoses stated in the manual. #3 #4 throttle body would just suck the fluid out of the other two and almost into the engine, i played and played with them and just cant get them to equalize right, and the fluid bounces and changes and when i put the vacuum gauge on it it would oscillate fast and couldn't get a good reading..i don't know what to do

 

I have similar problem, new sparks,new fpr, new air filter, and my bike not accelerate well and fast between 4000- 8000 rpm,i am waiting for answer.

 

there has to be some things im missing...i havent messed with valves or even checked them surely they arent out of spec already?? Im fixing to take the throttle bodies off completely take the start valves out and clean everything really good it might not fix anything but it cant hurt it