'99 Chevy Tahoe Running Rough or Missing?

[xjdrew]

I've got a 99 Tahoe with the 5.7 The passlock got activated somehow so the security light kept flashing. I changed out the key cylinder and the ignition switch which didn't help. Then, I changed out the CPU and it finally started, but now it's running really rough, as if it's not running on all cylinders. I actually bought a brand new CPU, which didn't work, but I put in an old CPU that I had lying around and that's what actually got it to start. Could the CPU be causing this or could there be some other problem just by coincidence? If anyone has any ideas please let me know. Thanks in advance.

 

[lowestjumperTJ]

any CEL's?

 

[xjdrew]

Ya it just threw two out, and both of them are for the egr valve

 

[xjdrew]

Well I just checked the egr valve with the instructions in the repair book. It stated to check the ohms and the voltage to and from the valve and everything checked out fine, but still pops the codes for it.? I'm thinking about taking the cpu to the dealership to get flashed but I'm skeptical that will work. Any other suggestions??

 

[transman731]

pull the egr off and see if it has carbon blocking the pintle from returning all the way.