Got an '89 camaro rs 305 tbi. The cars is idling like $***! Its hard to crank when it does start it Idles around 1600 then drops. When it drops it will idle up and down and if you tap the gas pedal hard it the motor hesitates really bad the goes back to idling higher then normal then drops back down. Its running very rich too. It was throwing trouble codes 15 and 21. I have checked for vacuum leaks with a fogger and havent found any

Parts I just changed:

IAC
TPS have it set to .6 v
EGR
The CTS by the thermostat housing
Fuel pump, filter, and the strainer in the tank
Plugs, wires, cap, rotor
MAF
O2 sensor

Who can tell me what to look for next?? also can the coolant sensor or sender in the block cause any trouble I will try and get a video of what the car is doing tomorrow. I have had this car for a year and a half and have only been able to drive it twice because of a long list of problems I have had with it. Wife is tired and wants it gone if I don't get it rolling soon and I don't want to have to do that so thanks in advance for any help....