My 1997 VW Jetta has a new/used 2.0L engine I just installed. It ran 30 minutes total time on gas that is over a year old and then it died idling. Now I can get it to start with starting fluid and it dies out shortly after. Runs really rough. It’s now at 1/8 of a tank and the fuel smells OK. Could it be a clogged fuel filter? Bad fuel pump?
Yes. Could be bad/contaminated fuel or just out of fuel. You may want to install a fuel pressure gauge to determine if you have fuel pressure. Here is one for less than $25 if you do not have one.
If you have fuel pressure than you know the injectors are getting fuel. The next step would be to determine if the injectors are getting pulse signals. This can be done with an injector pulse tester. This is the same kind I use for testing. It is quick and does not require removing anything. Just rest the tip on the injector while someone cranks the engine over. It flashes as it pulses.