Have a 98 3\4 ,4X4, V-10 that once in a while takes a notion to not start unless you ride the gas pedal and wont idle unless you ride the gas. Had my local dealer run engine dianostic and found nothing, trouble code shows nothing. All the dealer wants to do is nickle and dime me (nickle aand dime my ***) charged $95 for dianostic and found nothing.
ANY BODY HAD SAME PROBLEM OR ANY IDEAS TO A FIX.

 

check out the idle control valve... it may be sticking or on its way out. On the V10, I have no idea where it may be but you can download the manual from the merry christmas thread tacked to the top of the forum and see what it has to say. although it's a 2001 manual, the info there should be similar enough to yours for you to figure it out.

 

yup my 99 is having the same problem. I dont have any codes either. I changed out my map sensor, cause it wasnt sending the proper signal, and when i tested the IAC it wasnt working either. Just on my way to get one now. Is your truck running rich when it actually stays idling? Black exhaust comming out? Mine sure does and im hoping the IAC will solve that. let us know how it goes.

 

Steve are you talking about the Idle Air Control? If so on a V10 it is located on the intake next to the throttle body. IAC is the top one and the TPS is the bottom one.