1995 chevrolet silverado z71 dies out

[Tacklebox]

My 95 z71 dies when I turn on lights and heater battery good alternator good. Running rough no power too? Changed fuel filter.break petal gets harder when I give it gas to?

[carriedi]

I would check your exhaust back pressure.

the brake booster works on engine vacuum (unless you have hydroboost) so if you engine is running poorly and you open the throttle to accelerate you loose your vacuum. So, it must be pretty bad if it is affecting your brake pedal.

turning on electrical loads ( the lights, the heater...) make the engine have to work harder because they make the alternator work more putting a load on the alternator belt slowing the crank pulley.

you might also check your cylinder compression...

you should also look at your injector spray pattern. you should have throttle body injection so with your air cleaner and the air cleaner riser removed you can watch your injectors spray fuel down the throttle body.
https://www.youtube.com/watch?v=5A4a5OOGqPo

[tech3]

start with checking codes-
check for a vacuum leak- use the old spray trick.
FYI: Can also check back pressure with a vacuum gauge.
This should be a spider fuel injection YES? Anyway check fuel pressure.

How did test alternator as being good?

[carriedi]

95 should be throttle body. 96 should be CPI.

also, possibly weak egr valve problem could cause it to open under load.