1995 Chevy Blazer Idles rough, sputters, backfire

Ok, first did you reset the trouble codes? If not-- do so-- and see what codes come back. There can be many things that cause your problem, but lets start with the trouble codes first--reset them and we'll take it from there.

Ok, before we start let me say that some of these codes are all unique and (most likely) are not related to another. Also, I think it is impossible for all of these codes to just come up at once, but nevertheless I guess it could happen?

Lets try to get the engine to run better. Code P1406 is--EGR position sensor performance. This means your EGR valve is dirty and the pintal inside of the valve is stuck--there is probably a lot of carbon build-up causing this. Take the EGR valve off and look inside of it. See all the carbon (black stuff) inside of it--clean it up with some brake cleaner real good. Put it back on and see if the code comes back. If it does then change the EGR valve--clean it first because EGR valves are expensive. Sometimes there is a gasket where the EGR mounts--be carefull. If this gasket breaks or is damaged you must replace it--the gasket is cheap and should be replaced anyway.
The P0122 code is the Throttle Position Sensor (TPS) circuit low input. This could be a loose sensor itself--make sure it is mounted securely. The sensor (even if it is new) should be tested for proper function. This is easy. Get a voltage tester--make sure it is set to the DC setting--turn the ignition key on but do not start the engine. The sensor has 3 wires on it--the pink wire is the one you want to test first--this should have 12 volts to ground. The next is the dark blue wire--connect one probe to a good ground and connect the other probe to the dark blue wire by back probing the wire at the TPS. Now, open the throttle by hand--smoothly--observe the voltage. It should go from around.45 volts to around 5.0 volts--and back down as you close the throttle. The voltage should increase and decrease at a smooth consistant rate--if not then the sensor is bad. (Even new sensors). The black wire is the ground. Check it for continuity to ground or for voltage with the pink wire.

Please be patient with these problems, attack these two first and we will go from there. The reason for this is because the other codes may or may not be related to the engine running like it is.
When you get done with the EGR valve and the TPS sensor--reset the computer and see if the 1406 and the 0122 codes return. Keep me posted

BTW--sorry about the delay in getting back to you, I had some business the last few days to attend to.