Rob, i have been in the same spot as you, I bowled only with 2 fingers for a year with an average of 178, problem was that i could throw 240 and next game 140 lol, asked for some lessons.
My coach, former Wichita State Champion made emphasis on my approach, nothing else than my approach, have good fundamentals so then we can move on with release, hook, hand position bla bla bla and drilling specs, so IMO since I've been in the same situation as you, get good fundamentals, your game will drastically improve by just doing that, for me it was a full transition and start ALL OVER again, now im in the high 160s in 6 lessons, plus I do my homework.
P.s. it might take a while! im not a patience guy, but trust me, its worth it!