Hard start

So what is the fuel pressure at start up and what does it do once it smoothes out and runs ok?

The fuel pressure is a little low. How long has it been sense the fuel filter has been replaced? If more then a year then change it and see what that does. GM's fuel filters should be changed yearly. Let me know how it goes.

The computer will do what is needed to try to get fuel or it could be that a sensor is telling the computer to do something to change injector pulse or width. However I show a napa part number 3481 for the fuel filter? It is on the inside of the frame about under the drivers seat area. Thats what I show anyway.

Ok it may not have a fuel filter there is a time there where they didn't and the aftermarket shows they did. As for the fuel pressure needs to be about 60-62 at initial start up then runs at around 55 or so. Now if this is only at start up when its cold have you checked the coolant temp sensor? It can be ohmed with a meter. No I can't just give you an answer to your problems I need to ask questions and then try to find answers that make sense. I use Mitchell on Demand to get my info.

Have you ohmed it though. It may scan ok but may not ohm correctly, the scan tool picks up codes and such depending on the scanner. The coolant sensor can scan ok be out of ohm range the computer thinks it is colder then it really is. So if you would when it is cold ohm it and then get me the ohms with the temp at the time you check it ok. Thanks.

Never had the chance to finish more testing. You must remember doing this over web is not as easy as having it in my shop where I can drive it and check it out in person, it changes how you have to go about it to try and figure out what it going on. It usually take longer to. Sorry I didn't get it figured out quick enough however I did try.