Hello, my truck was running very well, then I had to get it smoged I took it down and it failed, very high NO max was 600 my truck put out 888. So I replace the cat and EGR + solenoid, coolant/thermostat, oil change and air filter. When I was test driving it, it has a hesitation on acceleration from a stop. Everything else was good, it accelerates smooth shifts fine.
Today I took it in to get smoged and it passed with flying colors, 16 on the NO now. But the hesitation is still there. It’s like the engine just cuts off and then picks up and your can go but only from a stop.

1992 k1500 5.7L Silverado extended cab

 

anyone?

 

Welcome to the forum. If those were absolutely the only things you changed and there were no collateral damages along the way, it could be some sort of fuel delivery problem. Maybe the fuel pressure regulator is faulty and not reacting to the manifold vacuum. The lack of EGR gases before may have masked the lean condition.

 

Thanks EinST. I thought about it and decided to try disconnecting the EGR Solenoid electronics and found that it ran very good again just like before. So I have a TBI rebuilt kit on order comes with a pressure regulator. Ill repost once I get it installed.

 

You're quite welcome. Check the PCV valve while you're at it (it's also supposed to react to the manifold vacuum)? Anyway, hope it works out for you.

 

got my TBI kit should install this week. Checked the PCV and it is working. ill update when i get the kit installed.

 

Then What happend... did it works for your truck?