69 Ford Galaxie 500 keeps trying to start even without a key

I went to start car from cold start. Pump gas few time then tried to start. It kept cranking but wouldnt turn over. Soon as I turn key off, the car still kept cranking. I pulled key out it kept going. I tried to push the gas pedal to floor to try flood it and the darn car started and ran for 10 seconds then went back to cranking. I put key back in and trued to start it and shut it off to see if it would shut down and it kept cranking. Then as it was cranking, it started to smoke from under the hood so u jumped out and disconnected the battery cables. This is the second time in the past eight months it’s done that. It happened once before my tune up and now. I replaced plugs, cap, distributor, wires, starter solenoid, both battery cables. Also did oil change, and I took car to battery shop and was told battery starter and alternator all are good and working properly. I also changed ignition key when I bought car and this happened maybe 6 months after switching it out.