P0120 / Starts, runs for a few seconds, then immediately dies

[idtpes]

Good Afternoon.  Have a 2001 GS300 that is throwing a P0120 code but also upon initial crank, while it immediately fires up, the engine quickly dies - within a few seconds.  The TPS was replaced by someone else (it does look new) and after the previous owner replaced the TPS, it still throws a P0120 code, but I am not sure if that is the cause of the engine shutting down within in seconds of starting.  It seems like while the engine gets enough fuel to start, it quickly becomes starved of fuel and dies out.  When the engine runs for the few seconds, it sounds quite smooth, it doesn't run rough, I can even accelerate the engine RPMs for a brief moment before it dies out.  I turn the key off, turn it back on to let the fuel pump charge up, then crank the engine and it fires right up, then dies shortly thereafter.  Perhaps a bad fuel pump and/or clogged filter?   Is the filter in the tank with the fuel pump or located elsewhere?  Or, is indeed the P0120 the cause of such behavior?  Any ideas on where the problem could be?  Trying to help a single mom with a teenager get back on the road.

Thx,

Paul

[RX400h]

P0120 Lexus: Code Meaning, Causes, Symptoms, & Tech Notes (engine-codes.com)

This web page has plenty of good information regarding this code.