can i take the 4.6 out of my 97 grand marquis and put it in my 1999 ford f 150 4.6l

 

You might have some oil pan issues, and intake issues. But if you do, just swap on the F150 specific parts that you need. Years ago, I did a similar swap into an 87 t-bird and put in a 302 destined for an F150, I had to reuse the t-bird oil pan and intake manifold put afterwards it looked and ran factory.

 

The heads are different. P.I heads vs non P.I. and about 20 hp

 

No, they are both non-PI. The 4.6 didn't go PI till 2001 model year.

 

my bad, I thought it was 99. In that case if I was him I would change it over to P.I.'s and the all aluminum truck intake and ditch the composite. A friend of mine had problems with the crossover and we found the aluminum one. 5 years later no problems. We installed E-Fans and a mustang temp sender in the crossover and it works flawlessly. Same set up as mine.