I put a new 5.7 vortec in my 1996 crew cab long bed and the egr was deleted. It’s running rough. I’m gonna give every detail to help u understand sorry for the paragraph. It’s back firing and feels a little under power. I do have an exhaust leak but even at idle it doesn’t sound like it’s running right. From what I’ve read I can’t tune a 96. Any help is appreciated thanks