I did not take it to a transmission shop, but to my regular mechanic. Definitely a long list of issues that point to more than what you are saying- clucking and noise if you manually shift into and out of 2nd gear. The CEL 2 error codes I posted, gas mileage now about 3 or 4 mpg lower than I ever got on the vehicle. Slow pick up and starts when you press on the accelerator. Now the cruise control will not engage at all.
Yeah I learned somewhere in my late teens to early twenties (after a good 3-4 rebuilds and replacements) not to EVER manually shift an automatic.
And some folks will tell you it's fine but then they're not the ones paying for the repairs, as I was told to put it in Drive and leave it there.
Only time an automatic needs to come out of drive is for it to go into Park and/or Reverse, and to come to a full stop before moving that lever.
Like I said it took several rebuilds before I learned, maybe in your case you can also get a used transmission put in, back in my days it used to cost $300-$700 between a used and a rebuild parts and labor...
I've heard prices have gone up but I think you can still get a used one put in for about a thousand, fortunately I took my lessons seriously at some point, haven't had to replace or rebuild one in a good long time.
You need to keep up on fluid and filter changes as well.
I was told that, too.
That one took a little longer to sink in than "don't shift it manually."
I believe I started changing fluid and filters in my 30's sometime, every 10,000 miles.