I suspect the starting fluid isn't getting past the throttle blade.
Also, pull a spark plug out and see if it's wet. If it is, and given the dropping fuel pressure, pull the vacuum hose off the fuel pressure regulator and check if it's wet inside. If it is, the regulator is leaking and must be replaced. Change the oil right away too to get the gas out that will have run down the cylinder walls. Leaking regulators are fairly common on GM trucks.
Saturday, February 14th, 2015 AT 8:25 PM