Long topic but basically describe it all.
Blazer 98. 4.3L
It was not used for a long time(3 years) , and finally revived it.
Done a full tune up, replaced all fluid and replaced spider injector.
Vehicle worked fine for about 5 months and all the sudden had a hard time to start it, it was stalling and hesitating, but finally kicked off.
Ended up dying whilst I was going up the bridge 30 min into driving. Was able to start it and idle it back.

Now the problems that are quite consistent are.
Stalling, hesitating, dying when gas pushed quickly, but when pushed slowly I can floor it.
When it is about to die, it kicks in automatically high idle for a moment to maintain vehicle going, then eases down to normal, once i press quickly, starts dying.
Code was shooting for bad MAP sensor, after replacing.... The same problems, and code.... bad MAP sensor.
I looked for vacuum leak, sprayed around with starting fluid to see it vehicle revs up, but couldn't find anything.
I noticed that my PCV is really filthy but still rattling, replaced it, didn't improve anything.
Now I'm thinking about fuel pump but it was replaced 5 years ago, and getting fuel.

 

Sounds like fuel pump or plugged fuel filter or some other fuel supply related issue - test with fuel pressure gauge connected to Schrader valve per sticky at top of 2nd gen forum (regulated to 58 psi with KOEO is OK for replacement MPFI spiders). Most parts stores have free loaner fuel pressure gauges.

 

What is the code and is it the only one?