Fuel system only or is there more fun ahead?

Here we go with new / more info. 95 S-10 Blazer 4 door 4X4 with: 4.3, Vin W, OBD2, EDI ignition, Central MFI.
Recently: new cap, rotor, plugs and wires, ignition coil, in-line fuel filter after disconnecting at the manifold and blowing out the fuel supply lines to and from the filter while tank was out. I didn't do the reurn line(s).
My previous fuel PSI testing indicated replace the fuel pressure regulator located in the Central Multi Port Injector. So I did this. Here are the results. When I use the jumper to the test conector for the fuel pump I get 49-50 PSi. When I clamp the return line down tight, I get 64 PSI. So, I dropped the tank and removed the pump/ sender assembly. Everything including the tank looked good and clean. I would expect this since while I was away from home a couple to three months ago I had to have a Chevy Dealer replace the pump. Anyway, I did a bench test of sorts. With the pump in a small container of fuel (Yes I emphasized safety- don't like explosions) I tested the pump with the PSI gauge hooked directly tro the pump. I got 64 PSI. I NOTICED fuel coming out of about a 1/4" high by 3/8" wide slot at the top of the pump. Inside this slot was what I believe to be a spring for a PSI relief valve. Is this usual or did they put in the wrong pump? More results: it starts slower than before and misses on one or two cylinders. Fuel PSI while running 49-50. Had to get it to 2000 RPM or more to nurse onto standard height (about 8") car ramps.
Another thing I should mention- My Code Reader is an AutoXray 2000. All I get from the Blaze is "Vehicle not responding". I don't think it's the reader cause i can read my son's 2000 Exploder. I also got the "Vehicle not responding" with a borrowed Equus Innova 3140 Scanner/Reader. The "Good Book" indicates it's time for replacing the CMPI. If you agree, what all should I be sure to replace along with the CMPI? ANY HELP? Any ideas on "Vehicle not responding?

A good fuel pump should put out 95-105 lbs of direct pressure.
You should test direct pressure at in line to fuel filter before droping the tank/fuel pump.
If you have the fuel pump out and it will not pump full pressure replace it with a AC Delco/delphi pump.
Do not even think about a Airtex or aftermarket fuel pump.
After installing new fuel pump test te fuel pressure system for running pressure and or fast leak down.

A 95 is a in between from OBD 1 - OBD2 COMPUTER SYSTEM and requires a engine capable scanner capable of reading 94 1/2 to 95 years.
The only true test on a fuel pump is to check the direct fuel pressure from fuel pump.
A quick test is to block off the return line and see if fuel pressure comes up to 75-85 lbs.
But do not run the pump at full pressure very long.
Also when testing fuel pump and pressure you need to tape a gauge to outside windshield or outside mirror and drive it on the road for 20 -30 minutes
until the pump gets has run a while to check for a pump fading out after hot.

Hard to start cold and fuel pressure testing guide line.
Check cold start fuel pressure.
Check engine running fuel pressure.
Check engine running on the road fuel pressure.
Then shut it off and watch for fast leak down.
Pinch off at rubber part or block off return line and check full pressure.
If pump has full pressure with return line blocked and low pressure without it blocked most usually the fuel pressure regulator is leaking or not holding pressure.
Later V6 and V8 gm engines should have 60-66 fuel pressure.
Cold start should be 64-65 lbs of pressure.
If you do not have full fuel pressure on a cold start the injectors will not squirt fuel.
Do not leave home without it.
Engine running should be 60-66 lbs pressure depending on engine load.
Full pressure with return pinched off should be 75-85 or more.
And if it has a fast leak down after shut off you have a leak in system.
Post back fuel pressure readings.

MT

Here we go with new / more info. 95 S-10 Blazer 4 door 4X4 with: 4.3, Vin W, OBD2, EDI ignition, Central MFI.
Recently: new cap, rotor, plugs and wires, ignition coil, in-line fuel filter after disconnecting at the manifold and blowing out the fuel supply lines to and from the filter while tank was out. I didn't do the reurn line(s).
My previous fuel PSI testing indicated replace the fuel pressure regulator located in the Central Multi Port Injector. So I did this. Here are the results. When I use the jumper to the test conector for the fuel pump I get 49-50 PSi. When I clamp the return line down tight, I get 64 PSI. So, I dropped the tank and removed the pump/ sender assembly. Everything including the tank looked good and clean. I would expect this since while I was away from home a couple to three months ago I had to have a Chevy Dealer replace the pump. Anyway, I did a bench test of sorts. With the pump in a small container of fuel (Yes I emphasized safety- don't like explosions) I tested the pump with the PSI gauge hooked directly tro the pump. I got 64 PSI. I NOTICED fuel coming out of about a 1/4" high by 3/8" wide slot at the top of the pump. Inside this slot was what I believe to be a spring for a PSI relief valve. Is this usual or did they put in the wrong pump? More results: it starts slower than before and misses on one or two cylinders. Fuel PSI while running 49-50. Had to get it to 2000 RPM or more to nurse onto standard height (about 8") car ramps.
Another thing I should mention- My Code Reader is an AutoXray 2000. All I get from the Blaze is "Vehicle not responding". I don't think it's the reader cause i can read my son's 2000 Exploder. I also got the "Vehicle not responding" with a borrowed Equus Innova 3140 Scanner/Reader. The "Good Book" indicates it's time for replacing the CMPI. If you agree, what all should I be sure to replace along with the CMPI? ANY HELP? Any ideas on "Vehicle not responding?

On the CMPI
What good book says replace it?
Or why does it say replace it?
Does the good book say how to do proper testing on it?
How many miles on it?
What makes you think it needs replaced?
MT

If it is working good I would just leave it as is.

The Auto Xray 2000 does work for this truck. You have to use the model specific cable, which is the blue one. If you use the green cable(generic OBD II cable), it will not read it. The pinouts are different than the generic OBD II on board connector.

Actually I was using the Blue connector while trying to read codes. All I got was "Vehicle not responding " no matter what i tried.
Thank you for your input . TMScouts

Check your cigar lighter fuse - there were reports elsewhere that this fuse also powers the OBD II port.