I installed the new filter last night. Thanks everyone for the pointers. The install was smooth, no rust anywhere as it has always been a central texas truck. The PO said the filter was recently changed at the dealer, but I couldn't find the service record so I wanted to do it to make sure.
I did find that the filter mounting bracket was loose. Looked like the 10mm nuts had come loose. Upon reinstalling and tightening I discovered that the 10mm mounting bolts/ studs just spun once they were threaded on all the way. The filter does seem secure now though.
Upon start up it hesitated for a few seconds, but then started and my idle was lower than it usually is at cold start up. Im usually a 2k at cold start, then it drops to 1500, then about 900 at normal idle. Now my idle at cold start up is 1500, then drops to about 700 normal. I did realize I left the gas cap off after a few minutes of it running so i shut the engine down and reinstalled the gas cap.
This morning I noticed a vibration upon startup that can be felt from my drivers seat. The idle will be steady at 1500 but I feel the vibration for about 30 seconds or so, then it's gone. If turn the truck off, then right back there is no vibration.
I drove around a bit today and most of the time it only does it from cold start,but did notice it once after getting gas. Again, just for maybe 30 seconds at idle, then it goes away.
This was my first time removing the EFI relay since installing my Airaid MIT tube about 100 miles ago. Not sure if it's related or not.
Any ideas? The truck seems to be running and driving great other than the short vibration at idle that just started after replacing the filter.
Thanks for any help.