1994 GMC 3500 7.4l Missfire issue

[steve-0]

im new to the forum. hoping i asked this in the right area. i am having a misfire issue on my 1994 7.4l. when cold and started up it idles fine. when put into gear and not let warm up it will misfire for a quarter mile and then go away. it will also misfire on a fast take off from a stand still but only when it shifts to second and only once. Cruising down the interstate it will randomly surge after 15min at 75mph then go away. i have done all of the below
Distributor change out
new plugs
new wires
new fuel filter
new throttle positioning sensor
new O2 sensor
new Temp sensor
new map sensor
checked and adjusted the timing. currently setting at 8 degrees. 4 degrees made it worse. it was at 6

if anybody has ideas please help. loosing my mind

 

[sparky]

check fuel pressure hot and cold min should be 12 pounds you say you swapped distributor to a new one what about the dist module and when all else fails do a compression check