Front Disc brakes heating up/ Need help?

Hi everyone, About 2 years ago, before I left for a new job, I was gone for 6 months, anyway I put a 454 full roller/400 turbo in a 72 chevelle. I pulled all 4 drum brakes and put a 4 new disc brake kit($1400) from SS396.com everything is great @ 1st, then after 20 mins of driving the left driver front starts to heat up(rotor,pad heats up and pulls the car down)(the right front is starting to heat up a little also, I thought maybe my Hooker headers were to close to my brake lines, I then wrapped my headers, same thing, I got a new caliper last week, no go. I remember my vac line to 9 inch booster got some oil in it from the PCV vavle now unpluged, but this started way before that, front left rotor/pad and disc gets up 250+ degrees when my back stays @ 120 on temp. Brake pedal is firm, brakes are great for 20 mis, then whats burning/cooking? What gives? help please!