Last week I went out to start my suv

Last week I went out to start my suv. Turned key and dummy lights came on and dinged and turned key to turn over and everything went dead. Took key out, popped hood, wiggled battery terminals, and it fired back up. Did not do it again until today, and did same procedure and it fired right up but stalled on me while driving a few feet down the road. When it stalled all my dummy lights were on, heat was still blowing, radio was still on, etc. Turned it off put it in park and it fired right back up. I pulled into my parking lot and parked and havent tried again. What is going on? I noticed my neg battery terminal is loose. And I replaced the battery the day before this started happening. Im hoping its a simple repair. Please help.