My 2003 f150 5.4 triton is running terrible. It shakes and shimmies when accelerating or cuts in and out and my check engine light won't come on. Any suggestions would be greatly appreciated.

 

Do u live in a colder environment, how many miles on truck?

 

IAT valve

 

I would start with that as well. Try cleaning before replacing...it is a 20 minute thing. Cheep starting point anyways.

Here is a handy link on cleaning the IAC valve...sorry, don't have one on the IAT sensor:
http://www.ford-trucks.com/forums/97...4l-triton.html

 

135000 miles on truck and yes it's southern Indiana where I live so it does get cold. Thanks everyone for the help.

 

Tune-up ???

 

I second the tune up. Sounds like bad plugs and or wires...

 

Very likely you have moisture in the spark plug holes. This will cause a misfire and won't always turn on the C/E lt.

When running, unplug the coil connectors. If the engine runs worse, that cyl is ok. The one(s) you unplug that make no difference are the ones you need to work on.

After I.D. ing the bad holes, pull the coils, if they are steaming, they have water in em.

Spray the plug hole out, pull the plug, if it's all corroded replace it. Then I would say replace the coil, but you can try to dry it out first.

If you have access to a scanner, look at Mode 6 data, it will show you a percentage of missfires per cylinder. C/E lt won't come on till the % reaches over 23%. My truck did the same thing, would always show about 19%, no light!

 

Thanks everyone for your input, I'm going to try all of these suggestions and I will get back to ya'll with the results....once again thanks its much appreciated

 

Could possibly as simple as moisture in fuel run some gasline antifreeze. My truck did the same thing for about a week before i figured it out. However at that time it was below 0. Still worth a shot though