wont pass smog

need some ideas. went to get smogged today and my truck wouldnt pass. the guy didnt really know what to do about it either. he said it didnt even finish the test which is good cause he didnt charge me. but the problem he did say is that it seems to be getting too much fresh air in the exhaust? it doesnt seem to have enough back pressure and the motor idles funny it goes in and out of range while testing. it will idle smooth then drop down . then go back up then drop down. stock motor with lc engineering header to 2.5 exhaust to stock cat to 2.5 pipe to cherrybomb muffler to 2.5 turn down tip right behind the back of the cab. it past fine last year. damn nevada and their smog check every year.

i would put a vaccum gauge on the intake manifold (the part where the throttle body connects, should be some ports on the right side, like the ones for the power steering pressure switch.) if the gauge doesn't show steady vaccum, mean the needle moves back and fourth really fast. this means your valve are out of adjustment. look under your hood the sticker has clearence thicknesses i believe they are 8 and 12 thousanths. they need to adjusted at operating tempurature. this a good tune up, cap rotor wires plugs and some 91 octane fuel will get you passing smog. also run the shit out of your truck before you take it in, you need that catilatic converter nice and hot.