Need some help in making the right financial decisions when it comes to purchasing a new vehicle with some career/life changes coming in the near future.

So the family vehicle we have now is getting up there in milage (200k miles) and is really too small for our family. So I have been looking for almost a year on purchasing a new vehicle, but due to availability, market, etc… prices have been ridiculous and I haven’t found anything I could reasonably fit in my current budget. Well I have recently found a vehicle that I think I can fit into my budget, but there are a few issues.

Issue 1 is due to losing hope and thinking this is the new “norm” for the market I spent a portion of my “saved cash” I was planning for the down payment. Well now I am considering on pulling a 401K loan to shore up the amount I am short for a comfortable down payment and will put me comfortably inside my budget, and then using part of my tax return (when it comes in) to immediately turn around and pay off the 401k loan. Is this simply robbing Peter to pay Paul kind of deal? Is this a dumb idea due to the interest I would have to repay for the 401k loan on top of the interest i have to pay for the vehicle loan?

Issue 2 is I have very recently been accepted for a new job with a new company that will include about 10k/year pay raise but will also most likely require me to move sometime in the near future (6mo to 1yr). Side Note: All of my current budgeting is based off my current income, not my future income. Is it dumb for me to be looking at adding a vehicle loan and hurting my credit when I’m going to be having to sell my house (which I have equity in) and possibly be looking to buy another? Given the above issue of a 401K loan I am not sure when my exact start date will be, or who or how all of my retirement/401k will be transferred, or if all of this will take place prior to me being able to pay back the loan. So is it way too risky to do the 401k loan this close to a possible major change?

TLDR: Needing a new vehicle, but dont have the same amount i had planned for a down payment, and also about to make a career change. Thanks for any help.