EGR Valve and Code P0300 and P0401
 

1995 Blazer 4.3 stock truck.

I cleaned the old EGR valve and also tried cleaning the carbon in the intake. Got the same codes again so I bought a new EGR Valve 2 weeks ago. Now the truck is running terrible agian adn the same codes are set again. Any help? I can still see some carbon build up in the intake, hwo can I get rid of it? What else may cause these codes?

While I am trying to figure this out the heater not started leaking. Never ends

When you say carbon in the intake, I assume you mean in the runner to the EGR, right?

You may have to pull the lower and clean everything back to the exhaust crossover port