Im driving a 1ge straight six toyota cressida,the problem on it, it starting sometimes not starting sometimes its overflowing the petrol on plugs like it dosnt burn the plugs,it it did starts is not a

Fuel system issue could cause a backfire threw the exhaust, like a weak fuel pump, plugged fuel filter or the strainer in the fuel tank, may want to look at the fuel system, may even be leaking fuel injectors. A fuel pressure test and bleed down test would tell the story on that. Also may be a weak spark, check to see if there is a nice white, bluish spark at the end of the spark plug wires, may have an ignition problem like a weak coil.