Sounds like something has come loose. Does it do this after hitting a bump for example?

I would get under the dash and check for any loose electrical connections. Also check the engine bay along the firewall...I believe the computer is on the passenger side of the firewall.

Gun it and run it!
1981 CJ5,258,T-176,D300,AMC 20,Dana 30,Trxus M/T 31x10.50, Rancho 5000's, GroundPounderFab front bumper, polyethylene gas tank, aluminum dash, AutoMeter gauges

What this country needs is unemployed politicians.