5.7 hemi rough idle and low backfire out exhaust any ideas

my 5.7 hemi has been sitting for a month and when i started it it started fine but after a few min of idling it began to idle rough and i could hear a few small pops from the exhaust. i recently replaced the o2 sensors and it ran fine when i covered it up could it be the same issue should i replace the sensors with chrysler brand sensors. also i am using a corvette fuel regulator and it has plenty of pressure any help is appreciated