Looking to purchase soon. I've been in contract on two homes already but buying in NYC is funnnn. Had no trouble getting approved for mortgages for both deals, but was not approved by co-op boards, likely due to strict DTI requirements (that aren't disclosed in advance!). I've moved on and changed my location, meaning my purchase price and therefore my proposed DTI will go down. There are a few things I'd like to do while I'm in between deals, just wanted to see how they may affect any upcoming mortgage applications.
What is the advisability of doing the below, in order of how badly I want to do them 
1. Refinance auto loan - I have the cash to throw a chunk at auto loan, and currently have 5 years left on a 7 year loan. I want to refinance to a 5 year, so not extending it at all. Should qualify for a much lower rate since credit has greatly improved since this loan was taken out....plus my payment will drop by close to $300. This will reduce my DTI by about 4%. Just not sure if the inquiry will be seen as a hindrance to the mortgage or if I just have to explain it. They may cancel each other out, or it may not be worth doing until after closing. Co-op boards are much more inerested in the granularity here.....they will look favorably on the lower payment.
2. Close a credit card. It has a zero balance, as do all but 1 of mine, and that one is just floating, paid in full bi-weekly. The highest balance that would be reported is never more than 5% of overall utilization. If I close this card, it doesn't go over 6%. This card is goig to be closed after mortgage closes....but they just charged me an annual fee. I would rather not pay it, lol. Will closing this card hurt me in any significant way?
3. Open a new rewards card, to replace a currently open secured card? The credit line on the new card would more than replace the secured card, but secured will never graduate and I have a decent chunk of deposit sitting with them. I'm now in a positon to explore paying for everything with rewards cards, so I am looking to maximize that strategy. This is lowest priority, as any new card bonus that needs a minimum spend amount will be difficult to achieve before closing since I am trying to minimize spending.
Happy to provide any additional details needed for advice. Thanks in advance!
Just providing more info - just got my 3 bureau report, and all are above 700 for FICO 8. My recent debt paydown is also not reported yet, so score should continue to go up.
My instincts tell me that the inquiry from the auto loan isn't nearly a big enough deal to endanger the mortgage. Same with losing the credit line/history from the credit card I want to close. But I've been wrong before
Well what's done is done but a few recommendations:
1) Unless you're getting kicked out as a result of DTI don't refinance; if you are, then refinance. I've never heard of DTI metrics not being disclosed, what loan program are you using?
2) The FICO 8 scores are useless, if you have the 3B look at the mortgage scores specifically as that's what's used.
3) You don't lose the history with the closed card, it will stay up to 10 years on the report; that said, it is one less card reporting $0 which depending how many cards you are might be some points in the margin (some of the mortgage scores are REALLY finicky on accounts with balances) but probably not a big deal.
4) Absolutely positively no new tradelines with the possible exception of that refinance. Sounds like from your FICO 8 scores you might not be in a clean scorecard which changes this a little (new accounts are basically w/e other than AAOA so refinancing isn't likely a big problem) but don't pick up a new rewards card until after the mortgage closes... plenty of time for that, put what's important first and that should never be a new rewards card in literally anyone's life compared to the mortgage underwriting.
