any ideas on what this could be,

it only started doing this, it is very sluggish now since it happened, it started when l was driving at a normal speed,

so it shakes, goes really slow, is really loud popping sound when shaking.

i am taking it to my garage saturday, but wondered if anyone had a clue before they sting me lol

well this would probably be more common if it was a standard, ut you didnt tell us. my guess would be that you are shifting too early, so the RPMs in the next gear are so low, you engine struggles to stay on. with an automatic, it would shift at the right time, but maybe it doesnt have to torque? this is a tricky one.

CHado

l wish l could hear the 'popping' sound.
My first guess is that your spark plugs are firing out of order, and two cylinders are fighting each other. But how could this happen after driving normally for a while? do not know.

This is a prank that some people play on others, to secretly reverse two spark plug wires on your engine, then sit back and laugh as you drive away, sluggishly and misfireing..

l have no good answer without more info..