i have a 94 f150 with a mass air 351w trickflow upper n lower r series intake gt40 heads trickflow stage one cam.. i have changed tps sensor iac valve and still have an issue... it will idle up in park or neutral but idle fin in drive.. and the last couple of days it has started idle surging at start up until it gets warmed up... i have sprayed carb cleaner between the upper and lower to see if there r any leaks and it does idle up some making me think its the gasket between the upper n lower.. could that cause these problems? there r no other leaks from what i can tell.. anything else i should loook at?

 

You may want to check your fuel pressure at idle and upon rev..

 

Ok.. But y would it idle up in park n neutral?

 

Because of a vacuum leak.

Once you put the shifter lever in drive the computer will adjust the idle to about 750 RPMS.

Bob

 

Park is the safest but you need to determine pressure especially @ idle. If it drops under load then you could have fuel filter issue or a fuel pump going bad .

 

Truck runs good other then this issue .. The intake gasket would b considered a vacuum leak correct

 

Yes if you have an intake manifold leak it would effect vacume and alter idle

 

X2

 

after sprayin some carb cleaner aroung the intake.. it seems that the fitting that is used for the brake booster is leaking.. gonna try and tighten it up without removing the intake.. i remember from insatlling the intake that piece had to be flipped around to line up the hoses since trickflow intakes themselves r flipped 180 to run on the trucks so mayb its just not tight enough

 

Don't foget to check the vacuum cannister (coffee can) for leaks as well.

Bob

 

Is there anything I could put on the threads of the vacuum fittings besides Teflon tape to help make sure it doesn't leak again

 

after re-doing stuff on my 89 f150. It did the exact same idle. It would idle up and down on cold starts. Turned out the computer needed to calibrate itself because it was sitting for so long unplugged.

It did it for about a couple days and one day i found the idle setting procedures and it went away.

 

It is VERY importand that the idle is "set correctly".

Yes, Yes, Yes !!!!!

Bob

 

Mine was the exact same problem. To the "T", it would do fine in any other gear besides park.

I found the TSB service procedures for setting the idle on here tho. To find it again is the problem....

 

well like i said i found a vacuum leak so it will b back together tonight and ill go from there