possible vacuum leak?
 

After starting my car, when I release the clutch the rpm's will drop very slightly. On a cold start, the rpm's are higher so this doesn't really matter. But on a warm start since the rpm's only go to the normal idle, it will cause the car to almost stall.

Yesterday I did a warm start and decided to just keep holding the clutch down, and the car stalled out. After the car is started, there's no problems. Is this a vacuum issue or something else? I have a boost/vac gauge and there's 16-18 in/hg at idle so I don't think there's a leak.

Mine idles at 20/21.

When you release the clutch (in neutral) you start spinning the drivetrain which will add a wee bit of load on the engine and dip the RPMs. All normal/NP

The warm start - almost stall incident should have kicked a code. I would not suspect a vacuum leak based on that... has it happened again?

The "almost stall" when it pulls the rpm to ~500 or so is every time I warm start the car. The only time it actually stalled out was when I kept holding the clutch in after the car started.

I'm not sure if it threw a code, because my SES light is on constantly from another issue, but I'll check the codes and report back.

I had my usual codes random misfire, bank 1 too lean, and a pending code for o2 response slow. I think these are all related to my fuel pump being weak.

Maybe check the fuel pump relay. I know my car was doing some interesting things that sound kinda like your issue. Replaced it and I was good to go.

Coil failing?

How would I check that? My new fuel pump is coming in this week so I'll see if that changes anything. I've already replaced the relay so it's not that.

Did the code say random misfire on a particular cylinder?

Nope. P0300