Ok, heres what it is. 1989 Formula 305 TBI motor is fresh around 10 to 15k. The problem I am having is that at 4300rpm or so it will make a popping sound back through the throttle body and other times it will make a garggling sound. It don't do it all the time so this is what gets me, I have tried to retard my timing and that did nothing. I run 93 octane everyday, is it possable that my valve springs are getting weak? Or maybe my coil is breaking down?
Guys please help me Running out of ideas

Thank-you
I DRAG 2