Chevrolet Repair: 00 chev 4.3 w no start, emission test, fuel pressure

Question
In a 2000 S-10 2wd p/u 4.3 "w" with 93k miles, I am original owner, intermittant no start, began about 2 weeks ago. Fuel pressure, key on, off is 60 lbs, start and idle 53-55 lbs, holds pressure if I leave it sit. Fuel filter just replaced, cap, rotor, plugs and wires, about a month ago. Will start on a wiff of ether, then once started will run fine and restart till left to sit and temp goes back to ambient. Then hard start comes back. I have noticed, if fuel pressure is relieved by hooking gauge up or when I changed the fuel filter, it will start right up on its own after key on/off and pump builds pressure. There are no codes stored in comp. and my code reader shows a green light to pass emission test. Any ideas on what possibly to check?

Answer
It is possoble the ECM coolant sensor located near the t-stat housing is out of calibration showing a colder temp that actually is causing the truck to flood out during ambient temp cranking.  For example if it is 60 degrees out and your sensor reads 40 it will not set a code but it will cause your truck to start hard.  You will need a scanner to read the temp at cold start up.