1998 Elantra manual
I had installed a cruise control after I bought the car.
This problem only seems to happen in the colder weather -10 Celsius and
below

I'm at my speed, I then press set, then the car immediately speeds to at
least 20 kmh over the set limit.
Sometimes it keeps on going (scary) but then it goes back to where I set it.
Sometimes after it has been on cruise for a while, it slowly starts
increasing speed 10-20 kmh over the set and them immediately drops off to
the set limit.

This problem seems to go away after the engine warms up.
I know this is not a Hyundai problem, but these seems a good group for
answers.  Any answers out there?

Thanks,
George