Overheating n drilling the thermostat

[Chewy4000 at aol.com]

Two days ago the temp whent between the two dots, so I sshut down the engine and looks around.
The 2yr old fuse ling melted big time, I had a spare, and actually found it.
My temp still stays, on these 100+deg days, right before the fist dot.
I have a new rad. new aux pump new hoses all new fluid, what else can it be.
My thermostat is maybe 3 yrs old, could that be the problem.
On normal days like today 80-90 the temp might be on 12 oclock or not much more but on 90+deg days that thing goes up like crazy.

I got to figure out what would help this, any info would help.
Also wht do you guys think of drilling a hole or 2 on the thermolstat.


Thnx in advance
Chewy