I have a 1998 Chevy 5.7 K 1500 truck with the trouble code showing egr valve. Replaced valve, checked passages, and truck still idoled ruff and ran ruff. Manual said to check terminals two and four, and it should have continuity. It didn't. So I did purchase and replace it also had no continuity between 2 and 4.. I also checked 5 volts to valve, and it was ok. So what could be my problem? Any advice would be greatly appreciated.