Re: 1989 351W EFI tweak
I assume since you say the Bronco is now EFI and that you want to convert to MAF, that it is currently speed density? If so, take my advice and LEAVE IT THAT WAY! You will gain no advantage by converting to MAF and it will only cost you a bunch of time and money. I know...I did the EXACT same conversion. You can tune speed density same as MAF, and you will get better throttle response to boot. MAF is capable of better gas mileage, and can easily adapt to engine modifications, that is the only advantage. Since you say you are leaving it pretty much stock, that's not an issue. Also, the 19lb injectors seem small to me for that engine. Use the formula mentioned on the Injector Upgrade article to make sure.
Fuel Injector Size = (Crank Horsepower x 0.55) / (# of cylinders x 0.85)