gslse running rough
 

hey guys ive had an84 gslse for about a year now and recently the omp lines melted so i did some research and made a blockoff plate im premixing 8 ounces of tc-w3 outbourd 2stroke oil to 13 gallons of gas at first it ran great then i washed the car and it barely idles and drives like a piston engine with a blown head gasket after about a mile its instantly back to normal it only starts if i shut the car off and let it sit for 5 minutes then when i start it the car runs rough no error codes and it has new cts plugs rotor fuel pump and filter any ideas
?!?!!?????

UPDATE!!
its only on warm starts im thinkin afm or O2 sensor