2004 Dodge Neon

Hat can make my car do this? Cause I need to go to the mechanic but I don't
want to get cheated cause I don't know anything about cars.

I was going over the bridge last night, it's a really long bridge and you
have to pay a toll, so I had to stop and wait in the traffic line to pay.
When I gave the lady the dollar I tried to hit the gas but my car wouldn't
go over 25mph and it would shake a lot, the engine light came on.

I hit the gas all the way to the
floor but it just wouldn't go and I couldn't stop on the bridge so I kept
going on the shoulder. I'm pumping the gas but the car is really weak,
then all of a sudden it jumped forward for a second and scared the hell out
of me, then it went back to 20mph all the way to first exit about half a
mile out. Once in the street it was fine, doing 45 all the way.

This is the fourth time this happenens, two times after waiting at the toll,
and twice when I was stuck in a traffic jam. Each time the engine light comes on, but goes off after the shaking stops.