Toyota Repair: Voltage Issue, fuel pressure gauge, lexus gs300

Question
Ted, I'm not sure if you can help me. I have a Lexus GS300 1999. I have taken it in and diagnosed but they found nothing. My issue is the car will run fine for about 20-30 min then completely cut out (wont die) but barely moves. I myself changed the battery and the battery connectors, it helped for a day. Any Ideas?

Answer
Posibly a loss of fuel pressure, it's not monitored by the computer and so won't turn the check engine light on, I would recommend having the dealer install a fuel pressure gauge and then drive the car until it starts to have the problem and then observe the fuel pressure reading, the only other thing I can think of since replacing the battery seemed to have helped is to have the charging system tested, the alternator may not have enough output to keep the ignition system and the fuel system going and starts draining the battery.