I need some help figuring out this problem:

I am in the military, stationed in Germany, so I can't just pull up to AutoZone and have them tell me what it is.

I have a 98 Ford F-150 XLT, 4.6L, auto, 2WD with under 50,000 miles.

While driving along with my foot set on the gas pedal, my truck will start decelerating, then accelerating, off and on- sort of like I am running out of gas, but I am not running out of gas. It never goes above the speed I am driving at, but continues to this until I take my foot off the gas pedal or give it more gas. It has never done this before, but it has been doing it alot over the last month. Any clues what this may be? I wish I had more info. to give, but this is it.
Any help would be greatly appreciated.

Thanks!

 

All it will be is guessing at this point.
Water in the gas will do what you discribe.
Failing fuel pressure.
Failing basic ignition control.
EGR sticking open.

 

Bluegrass,

Thanks for the reply.

After looking at your guesses, it reminded me of some other issues I had before. My CEL used to come on a lot, but if I disconnected the battery and reconnected it, the CEL would go away for a while, but eventually come back on. Also, I have noticed that my truck has been dropping below idle a lot lately... almost like it is about to stall out. So, based off what you have said, I am leaning toward the EGR valve. Is the EGR valve a repairable item or do I need to order a new one? Are you aware of A DIY test I can do to find out if it is malfunctioning?
When you say, " basic ignition control" are you talking about spark plug wires?

 

My 5.4 did this, kinda. I couldn't feel it so much as hear it. I couldn't detect any real change in RPM or power, but if I had the OD off, while pulling my boat on the breezeway, I could hear the engine change ever so slightly. It would cycle like this every 5 seconds or so. No Code thrown and I pretty much ignored it. But I did notice after I got a P0401 code, and replaced my DPFE, that I do not hear this any more. Just a possibility.

 

Thanks!

Any ideas are a help.

 

Get the fault codes, they are stored. Check for any leaks in the intake area. How's the fuel filter? Original?... clean the MAF...could be anything with out the codes to direct you.

 

Thx.

Brand new fuel filter 2 months ago. No leaks that I am aware of.

Unfortunately, F150s aren't common in Germany, so getting the codes is nearly impossible w/o getting my own reader, which is more than likely what I am going to have to do.