Accleration Problem

[skwan28]

Please bear with me because quite honestly I am a noobie when it comes to engine problems.

Ride: 240sx 89 fastback pretty much stock no recent engine work.

Problem: When I accelerate the car it begins shaking a little and doesnt pick up and when I am stopped and disengaged in neutral the engine shakes, it almost seems and feels like it is going to stall. However this is the catch it does this only after about 7-8 miles of driving (basically once engine warmed up). Before that time it works perfectly fine.

Things I tried:
-Replacing MAF exact same problem occurred
-Replaced with all new sparkplugs with sparkplug wires no change.
-Poured fuel cleaner in my gas tank

Things I plan to look at:
-EGR valve(was told to disconnect the top tube which connectes to the EGR metal housing to test if the car runs fine with it disconnected, possibly clean it with carb cleaner if it is the issue)

Please any suggestions would help if possible pictures of parts you guys are talking about, thanks in advance!