Vehicle Speed Sensor (VSS)
It's located on the tranny... jack it up and run your hands around it looking for the wire leading to it and tighten it up. No biggie! Also clear your computer... it should be holding a code for it showing low voltage signals. Just had long tubes instaalled and the shop forgot to reattatch the VSS and I to do the same thing.
Hope it helps!
My fourth pony:
1999 GT Vert, Vortech V-2, IPSCHASSIS SLA, Griggs GR40 Rear, Bassani/Dynomax, Fikse wheels, roll bar, too much to list...