0400 & 0401 codes

OK, now I'm pulling my hair out!! I have a 1998 Chevy PU and I have been getting code 0401 for over a year. About 3 months ago, I replaced my EGR intake, with a NON-EGR intake. In the last 3 months, I have replaced the vacuum pump, all 3 solenoids (wastegate-green dot, and both egr solenoids- white, and red dots), and the boro/map sensor (on the firewall). Plus, I have replaced lines checked, & double checked for leaks with a vacuum gauge. After the intake switch out, I not only got 0401, but now I get 0400 also.
I had a mechanic recommend changing out the eprom on the computer, but my 1998 does not have the eprom. Can anyone PLEASE help me??? I dows run great. And withe the non-egr intake, absolutely NO smoke during heavy acceleration. Thanks!!

You won't stop getting the EGR code because of the fact that you installed the non-egr manifold, The 97' and up Vin S motors uses the Mass Air Flow sensor to detect that the EGR is opening. You can't just unplug the Mass Air Flow sensor.
The easiest way to stop getting the code is to get another Computer from any vehicle, 98' and up that has the Vin F engine and the same drivetrain (2wd or 4wd).
You will need to perform a passlock relearn when you install the new computer.
The other option you have is to send your computer to JK or Heath and have it reflashed to Vin F specs with some tweaking.