running cold..need a t stat is my guess, like its stuck open. https://www.google.com/search?q=P012...m=122&ie=UTF-8
low voltage check the wires and fuse. http://www.obd-codes.com/p0102
the po300 is misfires multiple. last tune up? maybe time for one.
car off unplug the maf, then start it. if it runs better most of the time the maf is bad.