can you put a 6cyl in to a 4 cyl 99 cougar

It would be MUCH less expensive to trade your 99 4 cyl for a cougar with a V-6. The 4-6 swap would entail almost everything in the engine bay,plus the transmission, the exhaust system, all the computer controls and various other stuff l can not think of. The older Cougars were much easier.

Yes,
l saw a Hemi in a VW one time, And a J-35 Jet engine in a Pinto.
You can put anything in anything. Just might need a bigger hammer

Edit; He did just ask if it could be done, not how to do it..

Yes but you will have to change the wiring syst, and the brain (computer) then theirs a big chance you will have to change your trany,drive line,and motor mounts, but if ever you do get it in and running it will be worth the expense and trouble.
Good luck

Wow.way to speculate without any information people!

Your tranny is identical to the V6 tranny, as is ur wiring system. Your computer will require a reprogram.

Now, that said it will cost u a bit of money. The best thing to do is find a 3.0 Duratec V6 from a Taurus or Sable (all Duratec engines can be swapped in relatively cheap, but the Sable/Taurus variation is almost as easy to put in as a Cougar engine, its easier to find, & its definately worth the extra trouble).

If u can, try to find a scrapped SVT Contour also, as the best thing to do is make a hyrbid with the 3.0 & a few parts off the 2.5 SVT HO engine.

Go to newcougar.org & teamneco.com
They both have walk throughs with exactly what parts r needed based on the year of the engine u find. Almost all years only require a few connector pieces & then fit in perfectly. When l was working on doing mine (she got totalled partway through it) it was running about $2k for the engine & about $3500 for the complete swap, but l was doing the hybrid & rebuilding the Taurus engine l had to try to get the max power out of her-that was also two years ago.