replaced MAF but still getting code?

we replaced the maf wit the car but we reset the ecu and the MAF code still came up. car is a 1g with a modded in 2g maf, car ran fine b4 then coolant cap poped off and car starter to run like shit,, so we swaped in a 3000gt maf (it works) and then the car ran fine but still had code, y? is the 3000gt maf different than 2g maf