tbi fpr pressure changing

So I have had this issue for a little bit. I have the fpr just before maxed out don't want coil bind. in the morning it is cooler and it starts and usually runs at 22psi but slowly drops sometimes .5 to 1psi. Then by afternoon it is high 80's to 90's out and it will start at 20.5 to 21psi, then drop as low at 20psi. So I can have it drop 2 psi. In the winter I have seen as much as 23psi when in the 60's or below. I am wondering if this is normal, I have a fuel pressure gauge in the truck. I have the red spring 18-22psi with the tpi pump, stock fuel lines, 65pph cop car injectors. I replaced the diaphragm about 2 years ago with a acdelco rebuild kit. The fpr I have made adjustable. The fuel stays solid thru rpm just seems outside temp makes it change. I just replaced the fuel filter about a month ago.
Is it possible the spring(2yrs old) is worn out?
Is it possible the diaphragm is not up to par? it is acdelco, what are others using, I have seen jet and a few other make replacements are these worth it?
do the stock tbi fpr just suck and I need to go with external vfpr?

any thoughts?
as always thanks for any input

It's not uncommon for mechanical gauges to read differently at different temperatures. Are you using a gauge mounted to your fuel line, or a "test gauge" with a short hose the tees into the line? I would try to use another gauge and compare readings before making any changes.

I am using an electric gauge. there is a cfm-tech adaptor screwed into the fuel inlet of the tbi with a 1/8th npt port. Then I have a sensor in the port with wiring to the gauge.
http://marine-performance-parts.com/...843505774.aspx

The temperature could be affecting the sender or the spring, or both. Using another gauge to verify would be a good way to see what's actually happening. Are you seeing any drivability problems, or are your block learn values or AFR changing drastically?

Not really seeing any drivability issues wideband does very slightly show leaner. so at this point I try to datalog when it is at the middle fuel pressure for the most part tat way it is only -/+ 1psi. I just figured out how to add 2-3 more psi since I was maxed out with the red spring and there was no spring for the 23-27psi range. added a spring from a rear brake cylinder from a 95 c1500 inside the red spring and it gave me just over 25psi 1 turn from maxed out on the fpr, then backed it down to 2/3 the fpr and I an at 24psi which is where I needed to be. I took a test drive today with this and started with 24 and when I came home it was 23.5 but that was a 15 minute drive.

Any way my thinking is temp causing it but was asking around to see anyone else's thoughts

Maybe someone else with more experience will chime in