my 1999 ls 3.8l was running fine. It sudddely started misfiring. only got a p300 code. I replaced plugsand wires. Checked ignition coils and ignition module. They were good. Checked fuel pressure by priming the system without starting the engine with key on. Specs told me it should read 48-53 psi. 40 lbs was the max I got and it woul drop 2 lbs after a couple of minutes. It misses idling AND THROUGHOUTE DRIVING RANGE. iT IS BETTER AT HIGHER RPMS. I emptied the tank and put new gas in it. Did not change the condition. Is this a fuel pump problem. Thr car has 90,000 miles on it and it was running fine before this started. Please help.

 

What did you end up doing to finally repair it?