My 1993 Nissan Pathfinder's Chronic 'Back Pain'

I have a 1993 nissan pathfinder. for the most part the thing is a champ, few glitches here and there, mostly aesthetic. some seemingly mechanical and thus more concerning than others. its always struggled on hills, and start up it has always been rough on cold mornings but since the temp has dropped this year it seems to be having more than usual trouble grumbling to life. from start up it bogs down a bit (but picks it back up after a few seconds), starts this steady, slow ticking at idle and while its still there when driving (after warming up for a few obviously) its not terribly loud and to be honest its hard to distinguish where its coming from or if its increasing speed or volume while driving. all i know is that it showed up about when my goodold pathfinder REALLY started hating hills. and i live in the mountains, its a problem. my exhaust system is fine -passed "the rag" test, and while the thing is old, its been well maintained. anyone have any suggestions on the ticking? i relate it to the lack of power but cannot find issue with anything obvious.