i have a 2000 sonata with about 87000 miles and its started doing this thing where its sorta like driving itself. itll go up to like 35-40 mph without me touching the gas or break. the rpms go up to like 3.5 almost 4 in neutral and if i try to drive home like that because it does it just randomly so i have to get home with it but anyways if i try to drive with it i pretty much have to ride the breaks to sort of control it. anyone have any clue what it is? someone told me that it could possibly be the idle air control motor or valve whatever that part is but that costs like $350 so i wanted to try something cheaper first since im not even sure thats what it is oyah and that check engine light isnt on so i cant get a code

Check for a sticking throttle cable. Try spraying the cable where it attaches to the throttle body with WD40 or similar.

Could be the idle air control valve malfunctioning, although they usually get plugged up and restrict flow, causing a rough idle. If the throttle cable trick doesn't work, try taking it off and cleaning out the ports and valve mechanism really good with solvent.

It could also be a malfunctioning cruise control system.

BTW, the word is brake, not break.

thats what i think it could be too

Can't let this go by...
"WD"40 is for "Water Displacement". Despite the marketing, it's not really a lubricant and shouldn't be used as one. It rubs off too easily. Further, its solvent base may not be compatible with the cable jacket material. Tread carefully.