4 months ago befor I left to do military things I modded my '94 Z- T-56 conversion, SLP 51010 cam, u-pulleys, exhaust, etc...and I ran it with stock rockers, injectors, EGR valve and 02 sensors until now. I upgraded to Accel 24# injectors, replaced the EGR valve with a delco unit, new 02 sensors (bosch), got my VSS working ( hasn't worked until today), and tuned the idle to 800 RPM.

After I got my computer back from programming, it ran good in the midrange, pulled well down low, but lacked up top. I had a problem with the engine bogging and stumbling at idle after engine braking or running it hard. At this time, the VSS didn't work and the 02 sensors and EGR valve were stock. Today I replaced them as preventative maintenance as well as fix the VSS, now it idles fine, but makes less power. Still doesn't pull hard up top, feels kinda like stock. Anybody know what this might be? I'm kind of thinking programming, but I want to be sure before I act on that. Any ideas?

 

Well, not sure how you upgraded from 24# injectors to 24# injectors but...
How is the condition of the ignition system? Fuel system?
I kind of doubt it's the programming.

 

Do a seach... Bosch 02 sensors are junk. Gotta get them from the dealer.