Problem with cruise control

I drove with the volvo of my mother he has a subsequent pempomat in it bj. car 1988 bj tempomat 1989 i think i alsoo I drive with the car trying to do tempomat pressure set nothing passirt i am 40 have driven the tempomat made out on off position and on the highway has ér at once extremely strong waltzed I could not drive faster than 120 before walking my conjecture is because it is white smoke he burns water you know how or why ? please answer =(