Ahillsls

So I have a failed temperature gauge and bought a used set of gauges and same issue. Also I tried the different combinations of boards from the gauges (getting good at pulling the gauges in and out). They both start to work then sink way below cold. I have all new sensors including the one wire temperature sensor to gauge, Any ideas? I had the Computer rebuilt and it works good. One strange thing is when I changed the dash gauges the car ran different I had to adjust the TPS for the different gauges. Does weak caps in the dash gauges change the way the car runs?