Chevrolet Repair: Reoccurring Low Idle Cutout, fuel pressure gauge, gas tank

Question
On a '99 Cavalier (not sure about miles, it's the wife's car) we've had the fuel pump, fuel filter, and the No. 4 Injector all replaced.  We found rust in the gas tank and scrapped it out as best as possible.  The other day it started cutting out again.  It will start up fine but drop in rpms and cut out eventually.  It doesn't matter if it's in gear or if you maintain 2000 rpms.  Any ideas?  I'm having the mechanic call me at 9am EST.  I don't want to replace the gas tank but I'm not knowledgable enough to say no.  How much would that run nowadays anyway?

Answer
Hi Frank, First of all anything in the tank is no good. I haven't seen a tank on a car that new rust that bad INSIDE !! I think you need to replace the tank and filter again to start.
    When the engine cuts out they need to see if you lost spark or fuel pressure. This shouldn't hard if it cuts out the bad. They could watch the spark jump a gap from the coil to the wire. A fuel pressure gauge would tell them about the condition of the pump and filter.

Hope this little bit helps

Mark