Question

2000 Ford Windstar 3.8L is running rough pulled a code P1633. My van runs rough and idles rough, along with shaking

Answer 1

P1633 KAM (keep alive memory) voltage low

For this code you need to check the charging system,the problem about this code is that is does not cause rough idle and shaking. that is going to be with something else.

Answer 2

Start by checking the battery charge, and if the battery is OK, then check the alternator.

P1633 FORD Code - Keep Alive Power Voltage Too Low
Read more: https://www.autocodes.com/p1633_ford.html