What could cause surging and loss of power?

My truck will seem like it does not have enough power to complete the gear shift when accelerating at a slow-ish rate. It will then surge and backfire but return to normal operating conditions. If I hammer the accelerator it does not do this. Also, if I were to go in a roundabout where I yield and do not come to a complete stop, it will do the same thing as about, seem like it is underpowered and shift very late and roughly surge and backfire. I am looking for problem parts/areas at this point. I would like to try and tackle this problem myself. I have replaced the map sensor and have a fuel pump on order. I also plan to deep clean the throttle body. I have checked the throttle body for vacuum leaks but there seems to be none. I am just looking for knowledgeable suggestions because looking on the internet can be overwhelming with "parts and suggestions".