2002 f-150, 5.4, super crew, 51K miles. Trans just started slipping in third gear when the overdrive is on. With the overdrive on shifts from 1st to 2nd ok, but then when going to 2nd to 3rd the engine just races like third gear is gone. If I turn the overdrive off all is normal 1st to 2nd, 2nd to 3rd OK. Any ideas or suggentions before I take her to the shop. A friend told me he thought there was a solenoid switch in the trans that controled the overdrive and that had probally gone bad.