Hot End Temp Offset by 25 C?!

So I have been messing around with the E3D titan extruder, but I have not gotten very good results. This led me into inspecting the temperature of my hot end. I used a K type thermocouple to measure the heater block at various locations and the heating element itself. The heater block varied as you moved around it, which is to be expected, but I was reading low values. So, I probed the heating element and found it to be 25 C below the set point and temperature reported by Octoprint (or any other management software). I have a couple different heads for my Taz 5 and I think all of them have at some point been worked on/ had their thermistor possibly replaced. The thermistors I have on hand are generic 100k thermistors.
Has anyone ever actually looked at their hotend temp or seen anything like this?

I think the stock E3Dv6 uses a different thermocouple than the Hexagon, and as such the firmware settings and voltages may need to be adjusted. Alternativly you can put a stock hexagon thermistor in there. If its the same thermocouple for some reason that is reading a lower temperature, that would indicate a damaged thermocouple.

Piercet,
I am fairly positive that all my heads are running 100k thermistors. Even the Hex heads I have are coming in low. I havent checked the thermocouple yet, but it did read reasonable values for warm and cool water and ambient. I dont believe I am getting hot enough on the hot end because when I have the titan hooked up it will extrude a small amount fine (~3mm) once or twice but not multiple times in a row. This changes depending on how much I try to extrude, leading me to believe that the hot end isn’t hot enough and that the filament is getting hot enough if left in the heater block for a little while if left standing. Basically, I dont think I am getting the right amount of power to continuously melt enough filament. I did set the esteps correctly on the titan, and while it may be off slightly it is certainly close enough to get off the ground.