ive got a 97 f150 4x4 4.6 with an automatic the tranny has just been rebuilt with a shift kit and i have a kn cold air intake and a hypertech power three programmer and colder thermostat the problem i have is it wants to die when you pull into a parking lot or brake to a complete stop and then it has a horrible hesitation when under 2/3 to full throttle it will hit about 2000 rpms and stay for a good 3-5 seconds before it will kick in and throttle up i was wondering if any one else has had this problem or has any ideas id sure appreciate it

 

The Ideling problem sounds like the IAC sensor it is located on top the engine behind the throttle body. remove it clean with some carb cleaner and retry if it gets better then it is inedable you will have to change it to another. The hesitation at 2/3 throttle could be the programmer giving you problems, try setting it back to default and see what happens if it goes away then it is the programer. My two cents.

 

What lance said. He just beat me to it. :P

 

aight i took the programmer completly out and it still stumbles real bad when u try to throttle up its just started doing it this week its not throwing any trouble codes and ive gone through every sensor i can think of and im comin up with nothing the trucks got 129,000 on it and its not a miss i went through and changed all the plugs and wires out again just to be sure it sounds like its at bout 1200 rpms when u floor it but the tach shows round 2000 rpm then bout 3-5 later it jumps to 3000 then throttles up like normal and it runs perfectly fine at lower rpms to

 

Did you check the throttle position sensor, kinda sounds like it could be defective. and you did clean the maf sensor? soounds more like the tP sensor

 

yeah i cleaned the mass air flow sensor before my last post and it didnt make no difference ill check the tps and see if its still workin right the iac valve cleaned up the rough idle to by the way thanks on that one

 

So if you are saying that by cleaning the IAC it fixed the rough idle, then you need to replace the IAC it is only a temp fix and will go bad again. The reason I say check the TB is because if it is not working correctly then it will have jump problems like you are having, when you put your foot on the accelerator and turn the throttle the TB sensor sends signals to the main CP
U to give it more fuel, if not working properly then you waqnt get the right amount of fuel and then when you put the foot down more then it does make contact it will jump like that.

 

alright this afternoon it started runnin like it has a horrible miss all the time its only turnin bout 1500 rpms an im wonderin if it isnt a bad injector i dont know but i just finished classes at school today and im gettin ready to make a 2 hour trip back home so ill get lots of time to figure the problem out hopefully i can get her fixed up

 

well i couldnt get it figured out so i broke down and took it to the dealer this mornin and heres what they came up with. It had a bad pcv valve and hose, a bad 02 sensor on the left bank, the egr valve and thorttle body were clogged completly shut with carbon, the fuel filter was clogged and what was causing the lag, and the best one i have three studs broke off on the passenger side manifold which is leaking and throwing the right side 02 bank off and dumping 30% more fuel than required. well thats what i got so thanks everybody for all the help i sure appreciate it