Welcome to the herd!
May want to put vehicle specs in Signature & Profile, makes it easier to answer questions.
2001 ExST here also, owned since 2002@10kMiles, now 240kMiles.
Original V6~4.0L~SOHC Engine
~ Stock 5w30.BaseOil+Filter Swapped To 0w30\0w20.FullSyn+K&N, Replaced Every 6mth\5kMiles
~ Stock OilPan Drain Bolt Swapped To Valve
~ Stock OilPressurizedTimingTensioners, Replaced Every 100kMiles
~ Stock 192f ThermoStat+PlasticHousing Swapped To 183f ThermoStat+AlumHousing
~ Stock 1CorePlasticTankRadiator+16psiCap+Hoses Swapped To 4CoreAlumRadiator+18psiCap+SSFlex
~ Stock VacToClose HeaterControl PlasticBallValve Swapped To MetalPlugValve
~ Stock PCVValveCoolantLoop 5/16"OxBow+Hoses+Tees+ManifoldExchanger Deleted
~ Stock Coolant 50%Water50%Glycol+ThermoStat+RadiatorCap, Flushed+Replaced Every 4yrs\25kMiles
~ Stock Coolant Pump+Hoses+Fan+Clutch+Belt Replaced Every 100kMiles
~ Stock Ignition CoilPack+Wires+Plugs Replaced Every 100kMiles
~ Stock Exhaust OxygenSensors 3each Replaced Every 100kMiles
~ Stock ThrottlePositionSensor\TPS & DiffPressureFlowElement\DPFE Failed+Replaced At 200kMiles
~ Stock Alternator 130a
~ Stock Battery 650cca Swapped To 810cca Replaced Every 6yrs, Added MiniCharger+Bumper120vSlipPlug
~ Stock AirFilter Swapped To Larger\DeeperPaperElement
~ Stock AirFilter LowerHousing CheeseBox Mod
Original 5r55e 5Speed+OD AutoTransmission
~ Stock Filter & MerconV.BaseATF Swapped To MerconV.FullSyn Replaced Every 50kMiles.
~ Stock TransmissionPan wOut Drain Swapped To AfterMarketPan With Drain+Valve
~ Stock ShiftLever+OverDriveToggleButton Failed+Replaced At 220kMiles
~ Stock TransCooler Supplemented With Parallel TransCooler, Each With TempControlledFans
Original 1354 2WHi~4WHi~4WLo TransferCase
~ Stock Mercon.BaseATF Swapped To MerconLV.FullSyn Replaced Every 75kMiles
~ Stock ControlModule In PassengerKickPanel Failed+Replaced At 170kMiles
~ Stock ShiftMotor On TransferCaseRear Failed+Replaced At 200kMiles
Original 4.10 Differentials
~ Stock LimitedSlipRear, 75w140.FullSyn+FrictionModifier Replaced Every 75kMiles
~ Stock StandardFront, 80w90.BaseOil Swapped To 75w90.FullSyn Replaced Every 75kMiles
Original 4WheelAntilockBrakes
~ Stock RearDrums & Pads Replaced Every 100kMiles
~ Stock FrontDiscs, Pads Swapped To Ceramics Replaced Every 50kMiles
Original Suspension
~ Stock FrontEnd
~ Stock RearHydraulicShocks Swapped To AdjustableAirOverHydraulic+DualSchraders
Original 16x7" Aluminum WheelRims
~ Stock 255*70r16.AT Tires Swapped To 245*70r16.Mud+Snow For Better Torq+WinterPlowTraction
Original FogLamps
~ Stock Bulbs 2*9145hb3 Swapped To LEDs 2*9005hb3Cree For Better Visibility
Original CenterBrakeLamp
~ Stock Bulbs 2*T10mm922 Swapped To LEDs 2*T10mmFlasher For Better Visibility
Original InstrumentCluster & DashCenterPanel
~ Stock Bulbs 8*T10mm161 & 18*T5mm906 Failed+Replaced At 150kMiles, Sockets Cleaned+Tightened
More info at
https://2001fordexplorersporttrac.fandom.com