Hello, I have a 1988 Merc Grand Marquee, with the 5.0 Liter EFI.
I love this big boat as a sleeper but the Big ?'s are
I have not found much information on Motor/ Tranny swaps.
I found 1 post that shows a Turbo set up on the stock motor
But the post never gets into the Fuel / Air Ratio on control.

I am trying to find out if this frame is good to be a swap project.
Or If the frame is a odd ball and will be motor picky.
Due to width etc...

 

That marquis does not have the correct firing order as what you are thinking. Upgrade the cam and go to mass air and have fun with all the other mods that the regular fox guys are used to. including N/A or Power Induction.

 

There is a dedicated forum that I used a few times, GrandMarq.NET - Panther Headquarters

They helped me complete a few projects on my brother-in-laws ride....