Is there a fourth stress minimal pair?

Solution 1:

There are lots more of them. Go to one of the lists that tchrist posted links to, and look for ones where dictionaries will represent them with the same phonemes:

Discard,
Torment,
Transport.

If you want a pair that isn't spelled the same, how about

inker and incur?

These are definitely the same except for stress in General American English, and in many dialects of British English, including RP, the only difference between the vowels /ə/ and /ɜː/ is the length and the stress, despite the fact that they are represented by different IPA symbols,

Solution 2:

Inclined (sloping) Inclined (likely to do)