[mmc757]

I think that's just a pulse damper.
Tell us more about your symptoms.

 

[mmc757]

Where in the system is your pressure gauge installed at?

 

[mmc757]

In the last few years I've found that I need to pause between run and start for a second to prime the line whereas I didn't have to do that before. I've replaced the pump in the last year or so but that had no effect on the need to pause. Since its an easy workaround, I haven't really put much brain power into it but now you have me wondering if there's an inline check valve somewhere that I've missed noticing.

Regardless though, you should have no problem priming the line once the key is turned so the problem is still strange. Your statement that it acts flooded and runs rich really makes it sound like an injector problem. Since this is an intermittent issue that may or may not be related to temperature, its possible that your injector testing was not conclusive.

I would replace injectors. It shouldn't be too hard to find a set for cheap either here or on the facebook group. Even a junkyard would work although they would probably be a little more expensive that way.

 

[mmc757]

... It seems the thermostat went bad (2nd time while working this issue) The ECT went up to 230F+ and had no heat in car after 15 min which normally I would have heat. Coolant was definitely not cycling thru rad (hoses cool to touch) as I think about this I have a Failsafe thermostat from when I swapped out prior, so it should fail open. Prior to this I noticed the cooling fan was running on high 100%. I need to look at this more systematically I keep burying my head chasing a specific issue and lose sight on what ese is going on. LOL!

This sounds like a leaking seal on the water pump.
Does the heat work at higher RPM's?

 

[mmc757]

Take a close look at the bottom half of the water pump casing. There's a tell-tail drain hole there. If you have a snail-trail leading from that hole, than the seal is bad.

 

[mmc757]

Also, these references might help you organize your troubleshooting efforts:

PCM Manual

1999 Wiring Manual

Less overtly useful, but good background information:

OBD2 Manual

 

[mmc757]

It might be worth the trouble to do a compression test both hot and cold. I've never done it on this car before, I imagine it might be a PITA for bank 1, but I could see a small leak in the head gasket causing these symptoms.