Edit:
There should be no problem, provided that they were the same type, ie, two V6's or two I4's. I have the engine from a '96 Contour or Mystique in my 2000 Cougar with no problems, you wont even have to deal with the issue of return-vs-returnless fuel systems.
No , the 2.0 liter is not an interference engine in the 1995 Mercury Mystique
On a 1995 Mercury Mystique : There are ( 4 lugs for each wheel , total of 16 )
HOW DO YOU TEST THE COIL PACK ON A 1995 MERCURY MYSTIQUE DOHC 6 CYL.
right side of engine,is a big plastic bottle,do not open when hot!
free dowm load 1995 mercury mystique manual
... good luck bud, expensive and obsolete.
left rear of engine behind oil separator
I just looked at www.oreillyauto.com and found that for the 4 cylinder engine the alternator is $139.99 and for the V6 it is $169.99.
( 5W-30 ) in your 2.0 liter four cylinder or your 2.5 liter V6 engine
Look between exhaust pipe & block.
Bottom of the oil pan.
not charging the battery properly... check the alternator.