can cloged exhaust cause p0171 ,p0174 codes on chvy blazer

Here is a good read on the codes you have, see below, copy and paste

http://troubleshootmyvehicle.com/gm/4.3L-5.0L-5.7L/how-to-test- a-lean-condition-1

P0171 CHEVROLET - Fuel Trim System Lean Bank 1...Possible causes; Intake air leaks; Faulty front heated oxygen sensor; Ignition misfiring; Faulty fuel injectors; Exhaust gas leaks; Incorrect fuel pressure; Lack of fuel; Faulty Mass Air Flow (MAF) sensor; Incorrect Positive Crankcase Ventilation (PCV) hose connection...If the P0171 is combined with the P0174 code, it's very likely that the problem is caused by an intake leak. If there are no intake leaks, the next step is to replaced the air filter and clean the air flow meter. If the problem persist the front oxygen (O2) sensor may need to be replaced. The P0171 code could also be caused may be caused by one or more of the following: debris on MAF sensor causing an incorrect reading, improper oil level, low or high fuel pressure or Engine Control Temperature (ECT) Sensor reading inaccurate.

The po174 is pretty much the same.

The lean code could be separate from the car stalling out. try turning the key to the on position. wait a few seconds the start it. see if it stalls out. the fuel pressure might be bleeding off when the car sits