Wiring problem?????
 

I recently completed an engine transplant on my 323 .. i turned it on and it started fine.. i then revvd it up after letting it idle for a while and as soon as i took my foot off the gas it died.. when i treid restarting it it was turning over weird and the earth wire from the battery heated up and started melting the plastic on the wire.. would anyone know what would cause this and how i would fix it??..