go to dealership ask them which engines last longer.. the non PI engine's even on here u can check the 100K mile club see which year models have the more milage and which have the least amount of problem. but the non PI engine in 97-98 the 4.6L had already had all the kinks worked out of the motor cause i think they originally came out in like 95 or so... crown vics were first to have them i think it might have been 92... i'll have to check. but the 4.6L non pi had been researched and researched for much longer and in 99 when they changed the heads and the intake design and went to a more computer controled engine system they werent lasting as long.