questions about sensors and stuff

OK i have a 1991 mitshubishi galant SOHC 5 spd sedan.

This thing keeps giving me codes and it has trouble starting when its cold but once its warm its fires everytime. heres the codes it gives me
1)15 idle speed sensor
2)13 intake air sensor
3)21 barometric pressure
4)25 coolant temp
not sure if there the right diagnosis or what
but i have changed the
1) idle speed on the side of the tb and the one on the end of the tb
2) coolant the one beside the thermo housing that has a little black clip
3) Mass air sensor inside the filter can

but still i get these codes i have cleared the ecu several times. but it keeps giving them back to me what am i doing wrong please help

THanks
Dave