Chevy Blazer hard starting, white smoke

in the past I have a check engine light,O2,gas cap,manifold,:I had change O2, gas cap, spark plugs, fuel filter,I gas low in fuel, filed up in a gas station, (engine light never went off). The blazer started acting up, found myself on the side of the road not long after, it was like it has very low fuel, two day after i ad a fuel treatment just in case if have some water, didn’t help, empty the gas tank clean the injectors, but still doesn’t help, 4 weeks after we ad new clean gas started for a moment but doing all over again. lots of white smoke came out from the pipes this time, what is my problem please help me to fix it, need my blazer.