Thatboymarcuss

So I purchased my 2004 C230 about three months ago and it was at 97k miles. Shortly after purchasing it I noticed that when I drive it in the morning or at night, it kind of does a stutter at 5mph or 15mph, but only for about 10 minutes or so and then is fine there after. If I start the car up during the evening or day when it is more or less warm out it operates fine. Anyone have any suggested ideas on what it could be? I was thinking the tranny fluid needs to be changed but Im not sure. I would also like to note that my thermostat recently failed and is stuck open so the car is always running cold, according to the engine temp display, at about 60C all the time, could this possibly be the problem? I am actually getting the thermo replaced tomorrow, Nov 23 2014.