This just started happening yesterday.

At first, it was only when i was accelerating, and it would hesitate pretty bad.

But today, It idles horrible, and accelerates even worse.

I had the codes checked, and i got coolant temperature, and secondary air injection.

Do these affect idle? and how hard is it to fix this??

I bought a thermostat too.

 

change the coolant temp sensor. secondary air injection will not affect how the motor runs.

 

alright, wheres it at? and how do i replace it?

 

bbuummpp

 

also try lucas "a real fuel system cleaner. and or "seafoam" it.

 

You know... Instead of uselessly bumping your post you could have tried the nifty search feature... "Coolant+temperature+sensor+location" seems logical... Near the bottom of that search page is this thread:
coolant temperature sensor



But what were the codes your received. You may actually want to diagnose the problem before just replacing components.

On your idle issue, a few DIY preventative maintenance items may be in order. Such as cleaning your MAF sensor, throttle body (including the IAC sensor), and EGR valve; much of which is covered in various threads found in the Tech Article (DIY) section.