Help restoreing Pri 1.37_002 after MR1 update
 

I am having trouble going back to PRI 1.37_002 after i did the MR1 update i have relocked and let all the custom cabs run it showed it as being PRI 1.37_002 but as soon as i unlock and flash a custom rom it goes back to it some how. I have read alot of forums searching for it on here and xda but i havent found a solution. any help in the right direction would be awesome.