thermowax question
 

Can the thermowax cause a lean idle AFR if it isn't working properly?

Thermowax does not affect mixture at all. It only increases idle speed when cold. What makes you think the mixture is lean at idle? If this is an S4, the variable resistor can be used to adjust mixture and smooth out the idle.

me and my brother's friend were discussing components on the throttle body and i was curious if it would lean out the mixture at all because he is having problems with his car running lean. actually would anything on the throttle body cause this? lol

The TPS does.

so can vacuum leaks.

yup. Well we checked all that stuff on his car and didn't find anything wrong. but when we checked the pins on his ecu we found a few things.

well quick question, if the IAT sensor on the engine has a higher voltage at the ecu pin then its supposed to (like 3v instead of 1-2) on idle when its fully warmed up, would that make it run lean?