'99 Mazda Protege DX
 

So I need your help, I don't know barely anything about vehicles but I just bought a '99 Mazda Protege. I have had to fix numerous things on the car but got it running pretty good now EXCEPT when I start the car up when its cold, and dont let it warm up it makes a loud squeeling noise in mostly 2nd gear but sometimes in 1st. It only starts once I am moving, and in second gear, mostly slowing down . It is very loud. Really what I want answered is what I should be replacing. The car needed a front engine mount, when buying the car the engine wasn't sitting properly. Now engine looks good according to my friend. I put new brakes, and rotors, cv joint, and control arms. Brand new tires, and an alignment. As I said I had to fix numerous things, needed a little TLC but seems to be running great now other than that loud squeeling. It's rather embarrassing and would really like it fixed. My car has 210,000 KM on it. Is it the Serpentine Belt? Timing Belt? Help please !

Cheapest fix would be to look at the drive belts / serpentine belt.

probably a belt in need of adjustment