Recently got this 1993 Lexus SC300 from auction. We were told it ran but struggled to stay operating. When we brought it home it started up just fine. But a couple days later I go out to turn it on and she won't start.
We have replaced the fuel pump, fuel filter, and fuel pressure regulator. Anything helps.

Some things I've checked.
-Battery
-Fuel Line
-If a signal is being sent to spark plugs
-Ignition Timing Mark
-Timing Belt Looks fine

How did you check the battery?
Checked how?
What do you mean by signal? You checked for spark?
You mean with a timing light? Why did you replace the fuel pump?

Did you read through this thread?
https://www.clublexus.com/forums/ls-...capacitor.html

FIX: there was heaps of coolant and fluid in the spark plug valley (don't wash your engine bay)

Check for a coolant leak at the throttle body. Previous owner of mine had done some work and forgot (or lost) two nuts that clamp the throttle to the intake runner and caused the same coolant accumulation you described.

If you think it is a fuel starvation issue search for fuel pump ecu, they are known to have failures and cause intermittent bad running.

In addition to the fuel pump ECU, if you have no history on the main ECU have that included in your research…