92 K2500 5.7 misses at speed

[xgator]

I have a 92 K2500, 5.7, AT. It has developed an annoying miss. It is completely random. I can see it while at a stoplight (tach will tick down then back to normal about every 2 seconds). It is barely noticable under power, but if I try to cruise between 65-75 on the freeway, it starts bucking. If I step on the gas, it pulls up and goes, but when I try to cruise again, the problem re-occurs. Also, I am having an issue with the speedometer. It fluctuates all over the dial while I am driving and sits at about 20mph at idle. Any help on these issues would be greatly appreciated.

Thanks,

Gator

[nusch]

Check the vehicle speed sensor (VSS) since your speedometer is also messing up. If that is okay than I would check the pick-up coil since it is bucking at that speed.

[k-5_350]

had the problem on a 92 3\4 tone 454 and it turned out to be a grounding out distributer and caused the flux in the speedo and caused the 4l80e tranny to slip in and out of overdrive we replaced the distributer and the thing ran like a top. its not cheap but if you exaust all other options it fixed my problem

[383chevyZ71]

You might check the two ground wires up by the front of the motor. I had the same problem with the speedometer my truck after I put in a new motor and had forgot to hook one of the ground wires up