[david-b]

Welcome to AF!

Usually when running cold, the thermostat is not opening. I would check that out first and replace. Even if it still looks ok, I'd replace it. It's cheap anyways. Next, I would drain and flush the entire cooling system. Drain out the coolant, stick a hose in the thermostat housing, run the car with it on until the draining coolant is just water, and then refill properly. Make sure the heat all the way on and on full blast while doing this.

One winter I had a busted thermostat and the car would never warm up to full operating temp. Sucked because it was a cold winter, and the heater will only blow cold air because of it.

As far as the noise... not too sure. If you're feeling it in the pedal, it sounds like suspension work. Can you hear any noise when the engine is just idling?

Lastly, what year/model do you have?