Vehicle won't start

One day my van wouldn't start. The next morning it did. I hooked up an autotap scanner to it to read the codes:
P1870, P0135, P0121. Cleared the codes and took it for a test run.

About 2 miles down the road it stalled. Restarted it and barely got it home. Coasted it back into the driveway just shy of my garage. Read new codes:
P0300, P0171, P0300.

Freeze Frame data for the P0300 cope was this:
Fuel System 1************** CL-1
Calculated Load Value******** -2.35%
STerm Fuel Trim B1********** -3.1%
STerm Fuel Trim B2********** -2.3%
LTerm Fuel Trim B2********** 8.6%
MAP********************* 10.0Hg
Engine Speed************** 574.8 RPM
MAF Air Flow Rate*********** 0.65 lb/min
Throttle Position Angle******** 0.4%
Throttle Position Angle******** 301.2%

Does it run now? What is you fuel pressure?

P0121 - Throttle/Petal Position Sensor/Switch A Circuit Range/Performance Problem

P0135 - O2 Sensor Heater Circuit Malfunction (Bank 1 Sensor 1)

P0300 - Random/Multiple Cylinder Misfire Detected


P1870 - Transmission Unstable

Fuel Pressure was 0 PSI. I banged on the bottom of the fuel tank and the fuel pump started pumping again. It stopped at 40 PSI. After 2 seconds I lost voltage and it stopped pumping (priming). I jumpered pins 5 and 3 on the Fuel Pump Relay to keep 12 volts continuous at the pump and it pumped for awhile and eventually got to 55 PSI. I was able to start it long enough to drive it into my garage where I could drop the fuel tank. I got a new pump on order. Should arrive any day now. I got it off Ebay. It's about $100 cheaper compared to the auto parts stores. We shall see.

Based on your freeze frame data I think you would also want to look at your throttle position sensor. It goes from .4% to over 300%. Does your scantool allow you to see the output from the TPS as you push the gas pedal, it should be nice and smooth through the full range 0-100%. Might be worth checking.

I did look at the TPS sensor with my scan tool. I could see it move from 0-100 percent and it seemed to move smoothly everytime I depressed the gas pedal. I never saw it go over 100 percent so I thought it might still be good. I don't think the freeze frame data should have ever went to 300 percent though so I did buy one cause it was cheap enough insurance. I went ahead and replaced it and guess what. The old one had no spring tension at all, so it was definatly BAD!

If that's the case, I would start looking for a short somewhere in the TPS wiring or even the plug. Did you try wiggling the TPS plug with the Autotap connected and watch the TP angle? There is no way that should have been over 100%.
Also, did you try checking the fuel pressure as close to the tank as possible (and before the fuel filter)? That could help diagnosing the low fuel pressure and lead you in the way of a blockage instead of a faulty pump...

Forget all of this, I just re-read your edited reply......

Got Fuel pump installed. I now get 55-65 PSI on my fuel pressure. Runs like a Champ again!