Not sure about the 01, but most times on the earlier models the noise you are hearing is coming from the door stops. Getting some grease on the mechanism that holds the door open isn't easy. From the outside or the inside.
It could be lack of lubrication or the mechanism failing. Most times lubrication doesn't kelp for long, if at all. But a can of spray grease and a long nozzle is worth a try.
Ignored too long and it gets stiff enough, the sheet metal near the "Arm" mount can crack or tear.
It's called an "Arm, check" in the Jeep parts catalog. The Chryslerpartsdirect.com site is timing out on me or I'd try to give you a link. It's pretty much a Jeep only piece, I don't think I've seen one anyplace else.
The pop is often the shaft through the little wheel and/or the spring. The groan may be helped with grease.
