I have an 01 with 4.3 Vortec. I started having a small hesitation problem occasionally around 1800 to 2200 rpms awhile back. It did not happen all the time just once and a while. Recently it has become worse. One day it would not start. Checked spark and if it was getting fuel and all was fine. Kept cranking and it was so close but wouldn't fire. Drained the battery trying and then let it sit a bit. Tried jumping it and on about the 5th try it started. Ran fine but hesitation got worse. Wednesday b4 Thanksgiving had a hard time starting it but about 15th try it did. Went out of town for 5 days and it fired right up when I got back. Next day it won't start. Been to two shops about a month and a half ago and one says spider fuel injection assembly needs to be replaced but it could also be the tank needs to be dropped and cleaned. Fuel gage is nonfunctional under half a tank. Honostly don't know if that is why they suggested tank. Other shop suggested a fuel pump problem but I am wondering about that. Code reader when it was running says that multiple cylinders are miss-firing. Any suggestion?