My gains have come to a HALT

i dont know, i think its my training, lack of gear or something, im dieting down i want to be lean before i begin any real mass phase but i still think im wasting my time sometimes in the gym. i cant seem to transform my physique, i think its come to a halt. im 15% BF used to be alot fatter from before, and then bulking i got even fatter. anyway, i did the same chest routine for like 3 years straight. incline DB, flat DB and incline DB flyes. WTF was i thinking? and i never increase my poundage anymore for some reason i dont know what i was thinking, but i recently just switched over to incline barbell, flat barbell, and pec deck, what a pump, and i am increasing the poundage every time, and i lowered the number of sets a little bit. i do have a dense and full chest but its come to a halt for the last like 8 months or so. and my gains are always slow which is why i get on a cycle. im planning one now and its gonna be long, but i also need help on the training split. i dont want to train one bodypart per week, because thats too long of a rest and i want to get alot stronger. i do chest/delts/tris together, legs alone, back/bis together, i was doing a lot of volume the past few months, like 16 sets for chest, 12 for legs and all other bodyparts. sometimes 16. and i hit each part every 4-6 days about every 5. i dont really think anything is happening honestly. should i train each part twice per week or will that just be worse? i want a serious change here.

try this idea, you might like it.

mon:

chest, abs

tuesday
shoulders, back, abs

wednesday
rest

thursday
legs,

friday
Arms!!

Biceps, triceps, shoulders
All iso movements!!