Revving to high after starting
Check for vacuum leaks as this can cause high idle speeds and also too lean and that makes it hard to start cold or hot. Now if you have to jump it just to get it to crank over then you could have a bad battery, a draw on the system or a alternator with low or no output.
Would it help to take a battery cable off to reboot the computer ?
If you do that you loose any codes that might be helpful in location any other problems you have, so then you have to start all over again. I forgot to mention the IAC motor assembly, these can get carbon build up and holds the pintle open so you might want to check and clean both it and the throttle body with throttle body cleaner. If it iis really dirty you can use a small brass brush to get it knocked loose.
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