Engine Mechanical problem
2000 Toyota Tarago 4 cyl Front Wheel Drive Automatic 240000kms

Once cruising on the freeway after about 5-10 mins at 100kph, the car loses power and begins to shake almost as if it has spat a plug, once this happens it struggle to maintain 80kph with your foot flat to the floor and the engine screaming about 4-5000rpm, once stopped at the lights the car returns to normal and performs fine prrobably up to 80-90kph, but no problems driving around town ????

Any ideas what might be wrong with the beast ?

Dan.