Intermittent heat/ thermostat won’t go past 66. New install from June 2025. Went through the furnace and cleaned all sensors. Cleaned condensation trap. Adjusted gas valve pressures due to being a little high. Did fix a return flex duct that I noticed was half off. Replaced merv 8 filter with a merv 3 filter. Tested system. System has been running for over 30 mins now with no issues, and thermostat has gone up 2 degrees. System is heating and operating properly at this time. Due to new install and labor warranty, no charge.