Mopar 383 help please

So I ran the car again. Sometimes when I give it gas it pops (small backfire). I found out that the cars transmission slips (Awesome!). Seems hot but the gauge says its fine. Maybe the transmission is the culprit? I know there is something wrong in the valvetrain. Had a friend over and he said yup, I can hear the clicking in there. Sounds like it comes right under the intake. So Im thinking that the transmission might be making this car change rpms out of no where. As far as the vacuum issue maybe the springs or lifters?