Do I need to flash the ecm for my 98 f150 4.6 reg cab? I'm getting conflicting stories from 2 mechanics, one says yes, one says no. I got a used ecm from the junk yard and was sure to check the numbers to make sure they were exact, and when I installed the ecm the truck started right up(would not start before replacement ecm was installed). I'm having some other issues and I'm just wondering if its all going to come back to the computer? Ay help or advice is appreciated. Thanks