My truck keeps stuttering up hills or any time i engage the gas abouve 45 mph. I htink its the plugs and that one of them has gone out. I was goign to run it by you guys and c what other people might think. I have replaced the fuel filter today and it didn't help. The air filter is fine. What else might it be?

 

What year, model, and engine?

 

98 f150 4.6

 

If you were down one cylinder from a bad plug it would run like crap all the time. Pull the plugs and take a look. Also check the fuel pressure. Has the CEL come on at all?

 

So what would cuase it to run bad when im going up a hill? I dont know what the DEL is but if your refering to the comp then the CHECK ENGINE light has come on. What else?

 

If the CEL (check engine light) has come one then having the codes pulled will give you a good place to start. All I can do is offer suggestions without the trouble code(s). Does it run out of power at higher RPMS?

Loss of power under load could be the engine running lean, weak pump etc

 

The place i notice it is when i am goign up a hill or trying to gain speed at cruising speed. When i hit it from a stop i notice no differance. Its only while im driving.

 

May be a shifting issue then, does the tranny downshift, or does it stay in the higher gear?

 

its deffintly an engine prob. i have a manuel!

 

Scratch that then . Im leaning towards a fuel/sensor problem. Best I can say is get the trouble codes and let us know what you get. You can some more definitive answers with those. When you downshift going up hill does the RPMs increase at all? Sorry man, best I can do from here.

 

its all good. thanks for the help. I dont have access to a code reader so i will just see what happens

 

Most auto parts stores will pull them for you for free. Just go down and see what they come up with. I wouldnt leave it, could cause you some more/expensive problems later on.