C4 transmission help please

So after having a 3 spd inline 6 forever we added another Bronco to the family, a 1973 Ranger with a 302 and C4. the original 302 threw a rod and now it has a crate 302 in it. Here is the problem:

In park it idles a bit fast. At least to me. When you shift to Reverse the transmission slams into gear and if you are not on the brake it will take off on you. It actually chirped the tires at Sonic one day when I backed out. When you drop into drive it slams into gear too. Checked transmission fluid and it seems fine. Again I haven't had an automatic Bronco before so this is all new.
Any help would be greatly appreciated. Tips, advice, etc. This site has always been helpful so thanks in advance.

Sounds like the idle is set too high. It should be set under 900 rpm. Sounds like the obvious
Answer. That would be where I start.

If it idles fast in park, you need to adjust the idle. If you adjust idle low enough to idle in neutral but then stalls in gear, you may have a whole host of issues. I'd start by reducing idle in neutral and see what happens.

The biggest problem is cold, usually as motors get tired folks tend to increase the cold idle speed to correct for other issues and next thing you know it's idling really fast when it gets hot.

Thanks. I will try the idle. Now to find the idle screw..