Trouble getting hemi running right

so I have a 6.1 hemi its running a bbk 87mm throttle and a megasquirt gold box it has TTI Headers with no exhaust.
the car will run and idle but it backfires every once in awhile if I touch the throttle it just seems to die or backfire then die anybody had this problem? I called megasquirt and the guy said he figured it was a fuel problem I installed a pressure gauge and its 58psi please help lol