2004 MAZDA MPV Vehicle Speed Control Problems

I WAS ON I-75 WHEN I ACCELERATED HARD WHILE TRYING TO MERGE INTO A GAP IN HEAVY, MERGING TRAFFIC. WHEN I TOOK MY FOOT OFF THE ACCELERATOR MY VAN CONTINUED TO ACCELERATE AS THE ENGINE CONTINUED TO REV AT A HIGH RPM. I STABBED AT THE ACCELERATOR WITH MY FOOT TO SEE IF I COULD UNSTICK IT, BUT IT ONLY CAUSED THE ENGINE TO REV EVEN HIGHER - TO FULL-THROTTLE. I JABBED AT IT MULTIPLE TIMES TO NO AVAIL. I TRIED TO LIFT THE GAS PEDAL WITH MY FOOT BY JAMMING IT UNDERNEATH THE PEDAL AND PULLING IT UP, BUT IT FLOATED FREELY AND CONTINUED TO FALL BACK TO ITS FULL-THROTTLE POSITION. ALTHOUGH I WAS CONFIDENT THAT THE FLOOR MAT WAS NOT THE CAUSE OF THE PROBLEM I PULLED IT AWAY FROM THE PEDALS AND, AS EXPECTED, THERE WAS NO EFFECT. I WAS ABLE TO KEEP CONTROL OF MY VAN...

LATELY WHILE DRIVING MY CAR WILL SUDDENLY JUMP FORWARD. IT SEEMS TO HAPPEN MORE SO WHEN GOING FROM 2ND TO 3RD GEAR. ALSO, THE ENGINE IS BECOMING MORE HOT, EVEN AFTER ONLY RUNNING FOR A FEW MINUTES AND A STRANGE SMELL IS EMITTING FROM THE ENGINE. I HAVE TAKEN IT TO THE DEALERSHIP HERE AND THEY HAVE SAID NOTHING ABOUT THE SITUATIONS. THEY CLAIM, I AM PUSHING TOO HARD ON THE GAS, WHICH I DON'T DO. THEY ALSO SAY TO MAKE SURE I HAVE ENOUGH COOLANT IN THE ENGINE WHICH I ALWAYS DO. I AM AFRAID THE ENGINE WILL CATCH FIRE OR SOMETHING WITH THE WAY IT IS RUNNING. UNFORTUNATELY, IT IS MY MAIN CAR TO GET AROUND WITH FOR THE CHILDREN. THE CAR IS ONLY 3 YEARS OLD. I AM TIRED OF TAKING IT TO THE DEALERSHIP AND NOT GETTING AN ANSWER. *TR