My Hyunday Elantra' 94 won't start when hot

You have changed all the things that have no effect on the root cause of P0172. You need a new Fuel/Air Sensor. Your ECM is showing that the fuel air mixture is too rich, so it is reducing the fuel that is going into the engine. That causes the ECM to compensate by running the engine lean and that causes overheating. Buy a Denso sensor, they are the best.

Hyundai Elantra P0172: Fuel System Rich - Bank 1 - 700R4

https://www.700r4transmissionhq.com > p0172-hyunda...
Nov 21, 2018 - Elantra P0172 Code Defined ... P0172 is thrown when the oxygen sensors detect that the air fuel mixture is too rich. Bank 1 refers to the rich ...


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1. Error Code 24. Intake Air Temperature Sensor.
Solution:
Check the following:
- IAT Connector and wiring.
- Intake Air Temperature Sensor.
- Engine Coolant Temperature Sensor.
- ECM.
2. Rough Idling when the engine is hot.
The following are the reasons due to which the engine can perform bad when it is hot.
- Fuel pump control circuit.
- Fuel pump pressure.
- Fuel injectors.
- Non Return Valve clogged, located on the lower side of car chassis above the fuel tank.
- Engine compression, valve clearance, spark plugs.

Tell me what engine you have, petrol or diesel

here is some things you can take a look at

Elect Connections
air in fuel
fuel non return valve
condition of fuel
air filter blockage
engine mechanical condition
fuel injectors pump timing
engine coolant temp sensor
fuel quantity adjuster / positioning sensor
injector pump
fuel pump
ecm faults

check see if you getting spark if not.have vechicle code scan could have faulty ECM .faulty camshaft sensor and crankshaft sensor.make sure engine has been tuned up.replace fuel filter change spark plugs and wires. before engine can run need fuel and spark.either one not working car will not crank.

The other suggestions & more --would be a good place to start
some testing

So do that

Have things tested

There must have been a 'Check Engine' Light? When a 'check engine light' (MIL=Malfunction Indicator Lamp) is turned on, there is a DTC (Diagnostic Trouble Code) set/stored in the ECM/PCM (Engine Control Module/Powertrain Control Module). This code identifies which engine management system component/function experienced a malfunction. Once you pull/read this code, you may begin diagnosis. You'll need an OBDII (On-Board Diagnostics II) code reader. You should find a P07?? number stored (P07??... is a transmission code).

Can be many things...look at the air filter...if dirty replace it.
Dump in the gas tank a bottle of stuff to get water out...has methonal in it...in case water has condensed in the tank. When starting you might want to not stomp the gas pedal to the floor but rather push it to the floor and hold it there before and during cranking to start it....if the engine is flooding that should allow it to start but you may need to crank it 30 seconds before it catches. You can also have a weak fuel pump if it has never been changed.

Change the mass air flow metor

First change fuel filter and then change air filter. A turbo requires good air flow to spool-up correctly