Sounds like a vacuum leak somewhere on the intake, a hose perhaps? This allows extra air to get in and causes uncontrollable high idle, and usually sets a code, usu. "problem with IAC." (Computer closes IAC, idle won't drop, so it thinks the IAC is malfunctioning.) This also explains the cold-bloodedness, as the fuel mixture will be too lean, esp. when cold.
I'd start by examining all intake vacuum lines and make sure that any replaced component has an airtight gasket intalled. I once pulled an EGR valve for cleaning, and installed the gasket crooked, which caused a massive air intake leak. I got the same symptoms you have along with a code indicating a problem with the IAC. Reassembling with the gasket intalled correctly was the fix.
Check to see of your model year used an external fuel filter. (it's likely that it's integral with the pump.) If so, change it out.
Also, if you haven't already done so, clean the throttle body bore with a decent throttle body solvent, ie: CRC. Dirty throttle bodies that are so bad that the venturi sticks open are a bane. (I always clean ours at every oil change.) This would explain the poor idle quality.
Check for a throttle cable that might be sticking or kinked as well. And the obvious...check for a misplaced floor mat.