I just got a skunk 2 intake manifold installed and since the install i have had a messed up idle it stays at 1500 then goes to 1800 then drops and makes a bogging sound, the when you put your foot on partial throttle it bobs between the two when you engage the clutch and are driving as soon as the rpms are between those rpms it bucks....i have just noticed a slight crack around the tps sensor plug could this be the culprite?

 

are you getting a CEL code?

http://www.c-speedracing.com/faq.php

 

either the tps or the idle control valve. that what i think.