1995 Ford Aerostar engine poor performance

Engine Performance problem
1995 Ford Aerostar 6 cyl Four Wheel Drive Automatic

Sir, The ford aerostar was ok when I bought it in the UK. I took it to Spain driving all the way to Murcia. I used it for a year and one day the gear box failed and all the transmission fluid leaked out. I got the gear box reconditioned for a fairly large price at Benidorm and while recovering it drove down to murcia where 5 km away it broke down again and the trans fluid all leaked out. A second time I gave it for repairs to the gear box. This time when driving it out of the garage after about 8 kms the engine was smoking getting hot and not increasing in revs thus no action on the auto gear box. Thermostat was found to be ok and the firing order etc ok. At present it is still in a dormant state since a year. Please advise.