Intermittent acceleration while at cruise speed

[Credit2u]

I got a full tune up, new spark plugs, wires, timing belt, trans fluid changed, fresh coolant, oil change, etc for our big trip to Yellowstone.

Get 3/4 of the way there, middle of the night and it starts acting up and getting progressively worse.

Symptoms:
At cruising speed, it accelerates intermittently. That is to say, instead of maintaining smooth, even acceleration when at a maintenance speed, it’s like it gives gas suddenly every few seconds.

When accelerating, its fine, decelerating, its fine. I am really put out at present, it's Sunday and I'm like 800 miles from home. I almost wonder if maybe the timing wasn't set correctly, or if the plugs might be fouled? I checked to ensure that the air intake hose had not come loose or such.

Any help would be greatly appreciated!!!

[erikv11]

Plugs or timing would act up pretty much all the time, not just under certain conditions.

It sounds to me like the TPS (throttle position sensor) could be bad. But that is just a guess, and really the only way to definitively test is to swap in a working one. Driving by any junkyards? You can get a TPS from any 94-98. Really easy to swap on a NA, not sure if there is piping in the way on a turbo. Two little bolts, like 8 mm heads.

[jblackburn]

Unplug this line and block off the ports. Any difference?