Having just had all 6 of my injectors replaced, I'd have to recommend doing it. My '88 4.0 suffered quite a few problems (one of which that was caused by the old injectors was they dumped so much excess fuel the engine couldn't set up to pass an emission test) including unreliable ability to run at a curb idle speed.
Of course, my injectors *must* be gold plated at $117.00 per
but I didn't have to install them and at that price they were very nearly worth all the problems they made disappear...
Sorry I can't answer your question about a stock item upgrade, but just new over old made a huge difference in my old clunker...
Stephen