1993 Mazda 626 Cronos 2.0 5speed. Car is acting quite strange and rather quickly

What is your question?

Drove car during the day with no problem except I do know the battery was weak as cold starts were labored and wipers were slower than normal. Started car 4-5 hours later and got two minutes up the road and idle was a bit erratic (bouncing 800 - 1000 rpm. Normally sits at 750 when warm. Also noticed lack of power and what sounded like exhaust leak. Thought EGR possibly? Went to start car next day and of course battery completly dead. As this is a 20 year old car I don't want to invest to much into it and definitely don't want to replace parts by guessing.No indication from dash like engine light on or anything. Any help would be greatly appreciated