Good news. The used car dealer agreed to pay the mechanic for all repairs because the car was listed as "Good" condition with 70,000 mileage.
So far I know they replaced the fuel pump, filter and a fuel line. Still don't know why it's pulling the p0340 code after I installed the new OE sensor. I'll have to wait and see what they find with the #5 cylinder misfire. I have seen #5 and #6 misfire codes and #8 misfire codes on 8 cylinders caused by fuel rail leaks and/or fuel line leaks. When this happens the last 1 or 2 cylinders in the firing order can be starved for fuel which generates the code. I didn't smell or see any fuel leaks in the short time I was there changing out the sensor but I can't be 100% sure.
I may not post anymore since the job is out of my hands now. I'll be sure to pass this website onto the kid for future reference.