Codes P0507, P1122, P1121 04 Maxima, 5 speed, receiving codes P0507, P1122, P1121 MY mechanic has been unable to find out what the problem is

Symptoms: Engine service light is on, engine suddenly almost stalls when accelerating and to get to 40 mph you have to almost push down the entire gas pedal for it to run. When the engine is turned on cold, the engine hesitates for 2-4 seconds and then it goes to idle. After the engine has warmed up and while driver the rpm go sky high, then car decelerates, Like it is not getting any gas.1st-5th gears will not make the car move, twice while pressing on the gas pedal the car accelerates very real quick, moments later it will decelerate and engine stalls out, the idle is really really rough, erroneous idle, idle is sputtering. It is like the timing is off, bad gas type of sputtering, Have ruled out bad gas, the clutch & battery both have been replaced and the problem is still occurring after 5 minutes of driver when the engine gets warm. Throttle has been cleaned; there are no vacuum leaks or valve leaks found.

Bought 2004 Maxima 11/06 with 50330 on mileage 2 days later had problem starting car. Dealer said key was problem-wrong, replaced fuel pump twice-wrong, then after keeping the car for 2 weeks they finally gave up and just replaced the whole computer unit (ECCS Control Unit) was done 5/2007. Then the engine control module, injectors (due to 9 leaks), chain tens side guide, chain guide camshaft (2), seal-oil crankshaft front, gasket rocker cover (2), seal o ring, fltr asy oil, washer drain, enoil description...all that was done 4/2007.

March 2008 I complained that I thought my transmission was slipping and they told me I needed a transmission flush so I paid almost $200 for that and then in they told me my brackets needed replacing.

Now my car stopped on me while at a light restarted the car and press the accelerator and the RPM went to 2 and the car was barely moving. Which seems like the same issue as before just worst. To make a long story short now I need (2) cam sensor, crank sensor, and the mass airflow meter which after those get replaced the computer will need program costing $771 not including taxes.

I have a Certified Limited Limited Warranty and they say these items are not cover but the crank sensor seal and the camshaft sensor seal are covered. I called Gray Daniels Service asking what the difference was and he said the seal is included with the sensor but can be bought separate.

Then I went to the General Manager today as he was walking toward me he looks at his watch (3:45) and approached me asking can he help. I told him the ordeal and he basically threw me garbage saying there wasnothing he could do since it was late in the evening.