2008 chrsler crossfire, 55,600 miles , wont start cables clean battery testing good. jumped it still knothing , left it alone for a day came back started just fine , week later same thing. HELP???

Perform a Voltage drop test on starter circuit or have it done. Next check the immobilizer, ANTI THEFT systems these things are 10-20% of the vehicles I see for service aging and creating all sorts of anomalies! '08 old enough to have corroded grounds.

If you don't have the tools/means to do a voltage test, you can check the starter relay and at least eliminate that as a potential cause. Open the under hood fuse box and find the "starter relay," and swap it with one of the other similar-rated relays. (they're usually 40 or 50 amp relays). If it cranks you'll know it was a bad starter relay.