Hello forum dweller, I'm having trouble with finding/keeping stimpaks. Where can I find/buy them. Also I need tips on saving them. I also need tips on making money in the game. Please help, thank you for helping.

Doctors and a good portion of vendors do keep them in stock. Some mods might reduce the numbers of them or make them more expensive.

There are a few methods to making money. Kill and loot things, and then repair them and sell them. You can also sell ammo that you do not use or plan to use to make a few caps in the early part of the game.

If you have high luck you can get some quick caps by gambling in the casinos.

Also, in Old World Blues, finding the upgrades for Muggy and seed for the Biological Research Station. You can harvest plants (both from the wasteland and fom the BRS room) and turn them into salient green. Using the hotplate next to the BRS, make equal amounts Broc flower and Xander root. Give Muggy some coffee mugs and you'll get syringes and wonderglue.
1 broc flower, 1 Xander root, and 1 syringe = 1 stim. Once you finish OWB's Making Friends/Influencing People/Field Research quests, you can mass produce stimpacks.