96 Exp Gt40p In 91 Lx

The '96 Explorer's had the GT40 heads, not the GT40P's.

You'll want a complete MAF system (harness, MAF meter, ECU, sensors, etc) from the Mustang to do the converstion, not the Explorer The wiring harness and MAF meter will work, but you'll have to play mix and match with the sensors....and the ECU is totally different.. Was your prior Crown Vic engine converted to HO specs? Otherwise, all Crown Vic's were non HO engines. The firing order will tell you for certain.

The Crown Vic uses the standard 302W firing order of 1-5-4-2-6-3-7-8
The Mustang uses the 351W firing order of 1-3-7-2-6-5-4-8

If the Crown Vic engine was converted to HO and everything runs well, you might get away with just doing the engine swap and sticking with the Speed Density set up. Some ECU's are sensitive to major head and intake changes (like the differences between the GT40/Explorer head/intake combo vs the stock Mustang E7TE) and others are not. It's a toss of the dice really.

In any case, you'll want a Mustang camshaft in that Explorer engine and a better set of valve springs regardless. The stock Explorer pieces were non performance oriented, to say the least.