Intermittent momentary loss of power while driving
 

So there I go, cruising down the highway at a modest 68mph, not in the fast lane by any means, and every once in a while my 98 D1 just loses power and starts sputtering and dropping cylinders and acting like it's being starved of something (limited choices there), but when I take my foot off the gas immediately when this comes on and reapply the pedal a few seconds later it seems to have gotten its sh*t together and is fine, can be fine for a day, an hour, or months before it does it again. Almost feels like momentarily running out of gas but that may be leading the witness. Throws no codes when it does this and when I get it into the garage to check it out it is invariably running fine, so it all checks out fine. Chasing ghosts, man, chasing ghosts. We shall see what tomorrow will bring but any suggestions to help eradicate the demon would be most appreciated, thanks

I had what I would describe as the same issue, intermittent and sporadic, no rhyme or reason except that it all key always happened on the freeway.

My mechanic said it was a bad speed sensor(he said it was a mechanical unit that sent a signal to the ECU). I'm not sure if this is the same as VSS. Sorry, new to working on my car by myself.

He replaced it with a used unit and never happened again.

Good luck

I agree with the VSS, theres a rebuild article in the tech section, my local ace had a almost perfect washer in the "finishing washer" section, it has the right diameter and the center shoots out a bit, that with a new flat washer on the other side i rebuilt 2 from the junkyard for under 2$ (5$ for the two from the junkyard..)

I had a similar issue, usually going ~45-55 if you have an ultragauge, or another live obdII reader check the vehicle speed from the ECU, You'll see its probably over 100 for you even though the speedo seems to be reading fine.

I had (and still have) the same issue. I've replaced everything except the engine. Just learned to live with it. :/

^that

JD, do you know if you have carbon cutting exhaust valves? The early GEMS did not have the cc valves and they would stick/unstick and cause the momentary pauses in highway revs. It does happen in the same erratic manner as if it where the VSS.

I had sticky valves, exhaust valves or valve. It was number 8. I had a good valve job done and spring shimmed and that did it. The truck would run fine until highway speeds and then it would occasionally miss hard and feel like you were driving over railroad tracks. Then it would go away if you slowed up.

VSS
TPS
Either of those, the both are well know causes for this issue.

thanks, will have some time this weekend to poke around, tho this issue seems to have cured itself for now only to be replaced by a more consistent and annoying cold start issue

I experienced this issue again the other day. I purchased a TPS off EBay and when installed it I get the high idle issue so I swapped back to my original for now. I will be replacing my VSS soon and hopefully this addresses the issue. If not I will try the replacement TPS and see of my system will relearn or reset the values and take it back to a normal idle.