94 Blazer - impossible to diagnose

I own a 94 S-10 Blazer and no one (ie two very credible mechanics) has been able to figure what the problem with it is. Any suggestions would be very helpfull.
V6-4.3
130,000 miles
Regular Maintence is preformed
Symtoms:
-Very Rough Idle (will die with any prolonged stop)
-When Cold with any acceleration it becomes bogged down
-Even when hot it is irraticly bogged down, during acceleration and highway driving
(slight increase in frequecy of being bogged down with each usage)

No check engine light
No computer codes
No eccessive fuel usage

Noc sensors replaced
Spyder injection replaced
computer replaced (prom not replaced)
Rotor cap/wire etc. replaced

-Its now at a dealer and they have just informed me that the problem lies with the fuel pump and sending unit. They want $900.00, does that sound unreasonable? 01/03/04

Have you checked to see if your converter is plugged?

Have you checked to see if your converter is plugged?

Would a plugged catylitic converter possibly cause this problem?
I just cleaned the erg valve and my 4.3 W series...runs rough also..
the exaust really stinks at idle? [email protected]

OK i am havin almost the same problem. I did the egr and new plugs and new feul filter now i think i am going to take my catalytic converter off and see if that does it. If it is that then i will but a new one. Let me know if you come to any conclusions aswell. Thanks

On, my 4.3 1993 Wseries...I just had the fuel pressure regulator part of the CPI unit replaced...
The new CPI was $321. rockauto.com and now I find the internal fuel lines leak as well...

I had the same problem with my 94 , and found that the EGR valve was fully opening when it was not supposed to, and causing hesitation, and also a miss at idle, disconnect the EGR valve and see if the problem goes a way.