This problem appeared suddenly in my 02 Odyssey.
Starts up ok (sometimes with a slightly longer than normal crank time) but once it's started the rpms fall rapidly and the engine shakes violently. Sometimes it'll hold on and keep running with rpm in the low 100s, but usually it stalls.
If I try to give it gas during this time the rpm usually briefly spikes up to 3000/4000 before it rapidly drops back down and behaves as above. If I really stomp on the pedal I get greyish smoke that doesn't exactly smell like burning oil, but it's definitely not sweet smelling either.
No codes are being thrown.
Pretty sure this one is over my head, my guess was either a fuel issue or an airflow issue, so I've tried to troubleshoot from that angle:
Disconnected EGR valve, and later blocked off EGR ports entirely with a strip of metal.
Bench test main relay, it's good, also confirmed "3 clicks" while installed.
Checked air intake/filter, all clear.
Confirmed no bubbles in coolant, oil looks fine, no fluid loss.
Tried shifting to neutral immediately after starting
Disconnect battery for a few minutes to reset computers.
Tried starting while applying generous pressure on the gas pedal, this didn't help, but it spewed a fair amount of smoke before stalling.
I was thinking about pulling the throttle body to see how it looks, but I'm starting to think this one is just beyond my abilities, I'm shooting in the dark.
Is there anything else straightforward I should look at before I bite the bullet and call a tow?
Here's the background story:
My wife ran some errands, parked the van, and about 5 minutes later went out to move it to another space. At this point she was able to drive but observed "lots of grey smoke".
I started it up about an hour later and the idle was very erratic, dipping down to 100 rpm and engine shaking. Eventually it settled down and I was able to go for a short drive. Tried it again 6 hours later and it would no longer run.
I checked oil, atf, and coolant, all looking good.