And they were FI and not carb'ed.

do what i'm in the process of and just buy a box 5.0 panther. getting rid of my '98. i'll take a 5.0 any day.

Why?

Save yourself a world of trouble and buy either a 5.4 or 4.6. Make life a whole lot easier.

Because Boxes kickass is why.

What is worse than a non HO 5.slow SEFI? CFI!

Don't get me wrong, I still drive, on occasion, an 89 Grand Marquis and a 90 Town Car. But the 145 hp, low redline, wind noise, wallowy overboosted steering, make me want back into my 00 Grand Marquis pretty quickly. I won't mention gas mileage, the nice 2-3 chunk clunk AOD shift, etc.

Would I like a properly updated box? yes, I would love to take a coupe, add the aero box bits, a proper SBF that is EFI and an electronic controlled transmission (or a manual). But stock for stock, or lightly modified, going back to a box doesn't make sense.

well since you are going the 5.4 swap heres some good info.
first why do you want to swap heads?
Make sure the 5.4 is betewen 99 and 2004.

If you want to improve the 5.4 get a decent plenum and throtle body combo.
I,m using a ported accufab plenum with a 75mm accufab throtle body.
Remember that 5.4 love the extra air.
underdrive pulley will also helps.
what gear are you running right now?

Never even thought of an underdrive pulley, will do. Definitely will upgrade the plenum and throttle body.
Well I just checked my heads and they are not PI like I thought they might be so wont switch heads. I will just look to find a 5.4l with PI improvments

My gears are 3.55's

3.55 is agood start

just get a pi 5.4 and call it a day

yeah 2004_P71, Im only gonna do a few mods. In my Mind there are lots of things I want to do but my thoughts cost a lot more than whats in my bank account which I think many can relate too. Either way Once I find an engine and swap it out Im gonna be much happier with all the new found horses. I'm looking forward to an acceleration increase more than anything though.

Nice youtube vids also