What are symptoms of a bad spider injector

[blkmonday]

I have a 2000 astro. 120k recent plugs cap wires. Had meineke figure out a alternator problem awhile back and they mentioned I will eventually need a new spider injector because my van was occasionally tripping the engine light and would run rough. Last time I checked to code it was a misfire. This weekend the van ran pretty bad intermitanly. Runs and stumbles like it's going to stall..like a vacuum leak but then clears up. Used to only happen if the van was running then shut off and run again in short amount of time. I dont use the van much so I didnt care but now its worse. I did a spider valve a few years back on a 94 astro I used to have with success but I forgot the symptoms. Just want to make sure before I go pulling the intake. Any advice appreciated

[Vanfan]

I would do a fuel pressure test first, check for leak down. I would also pull the EGR and make sure it ain’t all gummed up and sticking.

[Car Health]

Rough idle.
Black smoke coming out of the tail pipe (when the engine is running).
Really BAD gas mileage.
Check engine light is on with misfire codes (usually a P0300: Random Misfire) and Air/Fuel Mixture too Rich Codes (P0172, P0175).