97 Chevy intermittent stalling and cutting out

I recently swapped in a MFI conversion I purchased from GM parts direct to replace the CSFI unit that I had. I also replaced the fuel pump at this time and gave it a major tuneup (crankshaft positioning sensor also). Whats happening now is I'm getting a stall at idle (infrequently) and the engine will cut out at partial throttle occasionally (seems to happen mostly uphill). I couldnt get any codes from a diagnostics machine but a MACS unit my local mechanic had told me it was the ignition module. I replaced this but to no avail the problem didn't go away. At least the parts store took the part back! Any help would be greatly appreciated. It's a 5 litre with the distributor ignition system, not HEI. My mechanic (neighbor) swears the fuel pressure is good and that its not the pump.

Remember 97 is a bad year on ign switches.
Go over all sensor readings on a good engine capable scanner.
Watch the TPS sensor for drop outs.
And check the camshaft retard setting.
Also double check that fuel pressure.

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 or hot and fuel pressure testing guide lines.
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.

Thanks for the advice. I'll be working on this after the holiday so if anybody else has more suggestions please tell me what your thinking.
Thanks

You nare welcome and let us know how it goes.
MT