melvin gray

Sorry but I've just registered and am new to this. I live in Australia and have a 98 model explorer limited. I have had it now for 7 years and it has 157000 kms. I have had the gear box re-built (twice by ford dealers but it only lasted a few months before playing up again) then by a transmission specialist 2 years ago and it has been good. All of a sudden it has started flairing again (as if the clutch would be slipping if it was a manual). I would like to keep the car but it has annoyed me in the past so much with this problem, I'm at a dilemma whether to perservere or trade it it.
Can someone let me know if this is a common problem with this type of gearbox or if I shouldn't let it worry me too much and just carry on. When the gearbox was rebuilt they said something about solonoids not working. I must admit when it comes to gearboxes I don't understand them too well. Any information would be greatly appreciated.