help please 89 blazer

while driving at about 15 to 20 miles down the road it starts cutting out if i accelerated into passing gear (floor it) it will run smooth till i back off ..will seem to maintain on level condition or down hill with just a hint of stutter im stumped here is what i have done:new ac delco fuel pump and sock,fuel pump relay ,filter,plugs wires cap rotor, coolant temp sensor,egr cleaned but was remarkable clean on its own,o2 sensor, i think thats it oh and new injectors (not re maned) only code it show is for a lean 02 condition witch doesn't help much ...please help any advice would be great

what motor and trans?

5.7 auto 4x4

check the egr valve <<<<<<<<<<<<<<<<<<<

did that and works fine and is clean.... ok today i thought id look at my dist and i found that the rotor cap was cracked at the shaff were it slides on was wondering could this be the cause of my headache...of corse im replacing it what a waste of money if it is as theres alot of new parts that didnt need but oh well new is better tthan old i guess