I just bought a used 1999 F150 XLT(115,000 miles), the other day, and I'm noticing a shudder when I slow down(coasting, not braking) around 55 MPH, any ideas what it could possibly be? The truck is probably due a tune up now, could it possibly be a misfire or something?

 

bump

 

I would guess fuel pump, fuel filter, tune up/missfire, or tires. How does it do under a load and at idle?

Is it throwing a check engine light?

 

I didn't know if it would be the fuel pump or filter because it usually does it when i'm deaccelerating, usually around 55mph, and it'll stop it completely if I barely tap on the brakes, but if I don't, it'll shudder a bit. I haven't been able to try it out with a load yet, but it idles just fine. Hope that information helps.

 

change your rims recently? I had changed my rims and they put the rear tires which were worn worse than the front on the front and they didnt ride well at all. also they used the wrong lug nuts and i had to order conical lugs. hope this helps

 

I had to replace a fuel pump on two separate trucks that would die if you let off the gas pedal to slow down. And the pump fixed it on both trucks.

 

If you haven't already, take a look at your u-joints. Even if you don't notice any squeaking doesn't necessarily mean there's no problem. I had a similar problem with my '99. My son told me of a shudder while decelerating. I pulled the drive shaft and found the back joint was shot.

 

^^^x2

 

does the steering wheel shake? and the brake pedal does not pulsate right? if this is the case,check the sway bar end links, ball joints and also the inner and outer tie rod ends.

Worn suspension bushings will cause this to happen. Also while the truck is in part move the steering wheel from side to side and see if it makes any noise.

 

The steering wheel doesn't shake any when it does it, and I'm not really sure what you mean by the brakes pulsating. Anyway, it seems the problem kinda fixed itself, at least for now. I have not inspected the u-joints yet, but I will be sure to do it when I have my next time off.