Intermittent starting issues

[JFK]

I've done a ton of searching and troubleshooting and hope to find some advice.

I have a 1991 GL automatic.

It will start when cold every time. Sometimes it will die, after about 15 seconds, but this hasn't happened in a while. Idle about 1200-1400.

While running the coolant sensor stays around 4.5-4.9 per the shoebox ecu monitor and idle does not drop while warm. Twice the van lost throttle response while under 30 or at a stoplight.

When the van is warm it will not restart. It will restart occasionally if you remove the coolant sensor wire, last time this did not work and the afm plug was removed and the van started and I was able to get home, completely fine.

Sometimes when I put it in park it will rev to about 2700 then drop to normal cold idle.

I've cleaned all connections with contact cleaner and wd40.
I've replaced the temp ii sensor and verfied that it read correctly with ice and hot water.
I cleaned out the icv valve, it vibrates and hums.
I looked for vacuum leaks but found none.

I would really like to figure out why it won't consistently start. Please let me know if you have any ideas.

[VicVan]

Have you cleaned all grounds? Check the FAQ, there's a well documented thread on their number and location.
_________________
'90 Little Blue Truck, 2WD auto, FAS GenV 2.0 NA (AVH)