Ok. I think I royaly P Oed the NCR. They sent a group of rangers after me telling me I had 3 days to Improve my reputation with the NCR. I blew it off and went on doing my thing. Three days later, Im in the middle of nowhere, and have three rangers minutes from attacking me. Is there anything I can do?

Do pro NCR quests. If you are vilified, wear NCR armor/clothing to be able to do the quests.

Ummm... listen to their warnings?

I kinda just blew it off/ was cocky enough to think I could kill three rangers at lvl 15.

I saved my game after a fast traveld to some gas station in the middle of nowhere, and they come like 2 minutes after that.

Set them up for a ambush.

run forrest...

I was once in a situation like that. I went through twice and just barely survived the second time around. Don't dispair, come up with a plan... Like leading them near a group of enemies and hope the extra fire power helps enough to win...

This. Or get a companion to help you out.

Its funny. I deliberately tried to get one of those groups to come attack me so I could get NCR armor. They told me I had 3 days to improve my relations with them. I waited and wait and waited, did all sorts of quests for other people, even attacked NCR controlled places, and they still didn't come after me.

You attacked NCR controlled places and got them redeployed to bolster defenses that were now going to be strained. Good show sir. Lol

Shoot them. When the NCR sent a group of Rangers at me on my last playthrough, I gunned them down with Maria. It was an 18 Carat string of bad luck for them.