Once in awhile, maybe a couple times a year, when I start my 95 GMC truck everything seems to be ok. It reverses just fine, when i put it in drive it seems to labor like dragging front brakes. Then i notice the tach & shift indicator are not working. Usually i would shift back to park, shut off truck & start over again. If the tach worked then I knew it would drive as normal. If it didn't work I would try again. There was no pattern as to when it would do this. The other day it did this & won't come out of it. I was told maybe the truck is not sensing any rpm's and trying to start out in a higher gear?