1996 Ford Explorer engine temp, gauge fluctuations

I have replaced the radiator cap, pressure tested it, it dropped about a 1/4 of a psi in an hour, talk to a couple people the said that might just be th hoses expanding. Not knowing if they were right I bought a block test kit with the blue dye, sucked out some antifreeze started the truck up gave it about 6 squeezes to get the air into the dye, the dye stood blue.
Boght an aftermarket gauge that one fluctuates between 190-225, so I grabbed my obd2 reader drove around with that for about a half hour coolant temp jumped from 210-179, that was the highest point it pretty much went to 205-179 while driving. Im absolutley clueless. Please help dont want to blow the motor.

I also noticed that everyonce and a while I get this running water sound coming from the heater core?

Yes I actually changed both twice once from napa, and the second time I ordered them directly from ford, same situation nothing changed. Changed out my tensioner pulley assembley today seamed to help alittle bit, know its going from 184-202 not fluctuating as fast, but I noticed when I shut the car down my upper hose colapsed until I started it back up is this normal, asked an autoparts guy and he said it happens.

Yes only when I shut it down

Actually just ran it outside at idle for about 20 minutes, and the top hose collapsed while running, radiator full of antifreeze pulled the cap no pressure?

Ok here is the run down from before gauge fluctuation, was driving home about a block away from my house my idler pully seized up and belt broke I costed into my driveway. Replaced pulley and belt, noticed I could push down on the tensioner pully to run the belt without a wrench, didnt think much of it, checked the fluid in the radiator it was about a half a bottle empty I have had the truck for about a year and a half but never checked the fluid in the radiator, I know stupid move, so I filled it about 2 days later I was going away for the weekend 3 hour drive, about half way there the temp gauge started fluctuating out of know were only got a little past 1/2 but would keep fluctuating from 1/2 to 1/4, got to my destination changed the thermostat, added coolant drove home a couple days later temp gauge was getting up to about 3/4 know, made it home without overheating. Called around some people said temp sender, went to napa bought one then it started to over heat, went and bought another one from ford back to square 1, fluctuating1/2-1/4, decided to do the radiator, water pump, a differant companies thermostat, got everything from napa. Changed all that and flushed the whole sytem. No change in temp gauge. Bought an aftermarket temp gauge to see what it was getting to, so I eliminated the factory gauge all knew wire and new sending unit for the gauge know that one was fluctuating to from about 220-170. Was thinking maybe the tensioner pulley was bad and making the belt slip on the water pump and fan pulley creating a fluctuation, replaced that temps are between 180 -205 so it got alittle better, still fluctuating. Was wondering if it could be a head gasket so I bought a block and headgasket tester kit with the blue dye I did this test like 5 times liquid stays blue. Went out and bought a new radiator cap put that in drove for about 20 minutes no change in gauge, opened the hood and the upper hose was collapsed, went out bought an upper hose put that in and put the factory radiator cap back on seems to stay had it running outside for about an hour no collapse, burped the coolant system to get rid of the air, hooked the factory gauge back up, right back to stage 1 fluctuating between a little over 1/2-1/4. Man this sucks, thanks for reading I know itsd a long one.

Thanks joe