97 F150 "Stumbles" at Cruise Speeds

[Cessnadriver]

Hi,
I'v got a 97 F150 4.6L 4WD.
157K Miles. Well maintained by previous owner, who I have known since the truck was new.
Here's the problem.
When at highway speeds, it runs fine, until starting up a slight grade, or beginning to pass another car.
As soon as the throttle starts to advance, the engine misses a beat or two, very noticeably. It seems like this could be a TPS problem to me.
Any thoughts? I've only driven this vehicle about 350 miles so far.
Also what recommendations would you guys have for a code reader for this and my wife's 2000 Windstar, as well as where I could get a list of error codes.
Thanks

[bkg4him]

I wonder if it could be the spark plug wires. A friend of mine has a Chrysler van that does something very similar to this, mostly when at high speeds or pulling a load. His problem was definitly the wires.

[mustangmike351c]

I would check spark plugs. if that doesnt help check your egr valve. it may be sticking open. its should only open when you are at cruise and close at idle and wide open or under load.