Hi Chris,
we had a similar problem recently with my wife's Nissan 4x4, it kept searching for gears, cruise would not work properly and it was running a bit rough plus the battery would go flat overnight and heater was a bit cool to say the least. I thought it was a battery problem so got that changed but problems continued, eventually after some considerable fault finding, I traced it to the thermostat, cost me 7bucks for a new one and after a 20 mile round trip everything started working correctly and battery has held its charge and has been fine since. Friend said that, if the engine cannot come up to the correct operating temp can be a cause of other issues with your vehicle management system. It's beyond me, but pleased it's running ok. Just thought I would mention it as you have similar issues albeit a different car. Good luck.