305 tbi issues. Advise??

[GM 4 Life]

My junk has me stumped. It's a bone stock rebuilt 305/rebuilt 700r4 & 3:73 gear w/ about 3,000 mi. on all. It has the following new or rebuilt items: rebuilt tbi, new egr valve, 195 t-stat, new coolant temp sensor, new fuel pump and hoses, new batt cables, battery and all new vacuum lines. It also has a new ignition module, plugs, cap n rotor & msd coil. It has good grounds on the motor & frame. It runs intermittantly sluggish taking off from a stop & under normal acceleration it feels sluggish at times running down the road to where there is more gas pedal pushed than at other times to maintain a set speed. It also has an intermittant miss that comes and goes.This all happens with the engine cold or warmed up to temp, but worse when cold. It also smells rich out the pipes constantly. I just figured my mileage up and i'm getting 21 mpg. I did verify that the timing is correct, but it seems to like 2 deg advanced the best. I am wondering if the dizzy shaft itself is worn out or its the tps, map, esc, the fuel injectors or???? giving me this problem. The injectors look to have the correct spray pattern. Any info or guidence will be greatly appreciated. Thanks in advance.