94 f150 5.0l automatic, no throttle going down highway? Intermittently.
 

I was driving about 65mph down the highway and the gas pedal went soft, and the truck slowed down as if I weren't on the gas at all. If I let up and hit it again it wouldn't accelerate. Once it got down to about 40mph the gas pedal would work again like normal. It just started and I'm not sure what it could be? Any help what to check first? It happened several times over the course of 15 miles.

Are you saying the pedal fell away from your foot? Or that the engine just stopped responding to it? Think carefully about what actually happened.

Put a fuel pressure gauge on it as this caption describes:

https://www.supermotors.net/getfile/...ssuregauge.jpg
(phone app link)

And read these TSBs:

https://www.supermotors.net/getfile/...11pipstall.jpg
(phone app link)

https://www.supermotors.net/getfile/...edefective.jpg
(phone app link)

https://www.supermotors.net/getfile/...0211shorts.jpg
(phone app link)

Also, read these captions:

https://www.supermotors.net/getfile/...ail/07done.jpg
(phone app link)

https://www.supermotors.net/getfile/...l/evpgraph.jpg
(phone app link)

it didn't fall away, but there was no pressure behind it if that makes sense.

That's psychosomatic - your imagination, when the engine doesn't respond the way you expect. There was no real change in the pedal feel or throttle return spring - it was just the engine stalling out. It would feel the same now if you sat in the truck & pressed the pedal with the key off, but your expectation is different when you KNOW it's not supposed to respond.

Is fuel filter plugging up? Id check it.Drove a 93 vortec 350 chevy that done this...If you barely layed foot on pedal it would gradually accelerate...but,if you tro ped it...forget it ...fall flat on its face like you went into neutral. Is this familiar.JMO