Where to start?

I just picked up a 2004 Econoline e350 6.0 completely stock. It seems to have an injector issue thats not too bad at the moment but theres not throwing any codes or a CEL so im going to run t6 with rev x when its ready for an oil change.

My question is, what mods are best to prioritize? What i have on my to do list is,

Programmer,
4" exaust,
Egr delete or upgrade,
Cold air intake,
Oil cooler upgrade,

Is there anything you guys would not do? Or add to?

Thanks in advance,
-Ryan