2000 blazer running too rich at start up
 

I went to autozone after check engine light was on and got the OBD check up and it said error codes PO175 and PO172 with multiple reasons for possible solutions to fix. The car seems to act like it's being choked too long after it's started and then after about 5 minutes it seems to run fairly normal.This occurs every time it's turned off and restarted even after it's warmed up.I replaced the two O2 sensors and still get the same results.I took it out on the highway and it ran strong with no hesitations so i don't think it's fuel pressure or injector problem.At start up in the morning it's a little hard to start but does after a few tries.I was told it could be the MAF sensor or fuel injector malfunction but the the car runs ok after warmed up a few minutes.Would this be a faulty MAF sensor that would malfunctioning at every start up or what ?

Have a look at these:
P0172 - Fuel Trim System Rich Bank 1
P0175 - Fuel Trim System Rich Bank 2

This can be caused by the EGR valve if it is stuck open. Basically, the exhaust gases which are being allowed into the intake by a leaking EGR valve displace oxygen causing the mixture to become rich (oxygen lean=fuel rich).

I would try cleaning the EGR valve first and see how it reacts.

egr cleaned
 

I took off the EGR valve and soaked it in carb cleaner without getting any on the electrical connection and put back on and it seems there is no change in problem yet.Is it normal to have, what i think is, a little too much water vapor coming out of the exhaust pipe ?

did you ever fix this? I have a P0172 and P0175 code to and is wondering did you ever fiqure it out?
1997 Chevy Blazer 4.3l 202k miles

could be a coolant temp sensor.http://www.asashop.org/autoinc/may98/techtotech.htm