My 01 f150 crew cab recently went in for new spark plugs. When I got it back the transmission seems to slip in OD. when it gets up to 40mph the truck just revs. I noticed the tran oil down almost a quart and I added some but that did not help. Could something have been disconnected accidently or is it just a coinicedence and the tranny is now gone? If it is bad should I get a new one or rebuild this one. It has 130k on it.