BACKSTORY:
So I recently swapped in another stock VQ35DE engine. I got the new engine to run after I finally figured out that my starter didn't have a good ground. Once I grounded the starter directly to the negative terminal, cleaned the throttle body and did an idle relearn I was finally able to get it to run and idle. As soon as I got it to idle I put the headlights in, the bumper on, the new trans pan on, and connected the transmission to the radiator. Other information: the engjne is a rwd engine with a swapped awd lower oil pan. It has a new front passenger cv axle as well. I am using the throttle body from the old engine.

THE PROBLEM BEGINS:
It was completely buttoned up so I decided to go for a test drive. I started it and it wasn't running as well. It sounded kinda like a train chugging along very slow. Pretty rough and some shaking. I wanted to see if it would at least move a foot or two so I put it in reverse and while keeping it alive with a little bit of throttle I tried to drive and nothing. Revving up very gently and not high at all it didn't budge an inch. So I turned it off for fear of hurting something.

CURRENTLY:
It will not start back up. If I try to start it after a day or two I get maybe 1 or 2 seconds of some rough firing with the rpms varying and then it dies. The more I try to start it the less it works until it just cranks and doesn't fire at all.

These are some codes I got back when it was actually running and before I buttoned up the bumper, hood and headlights and everything.
P1122: Powertrain, MFG, Fuel and Air metering, Fault: 22
P1121: Powertrain, MFG, Fuel and Air metering, Fault: 22
P0335: Crankshaft position sensor 'A' circuit
P0123: Throttle/Pedal Poston Sensor/Switch 'A' Circuit High Input
P0223: Throttle/Pedal Poston Sensor/Switch 'B' Circuit High Input

Any advice would be greatly appreciated! Thank you!

 

If the starter didn't have a good ground you probably forgot to reinstall the primary engine bonding jumper, it should be connected on the right side of the timing chain cover and the other end lands on a 2 hole lug bolted to the chassis directly below the coolant reservoir.

 

Here's where it should be landed on the timing chain cover.

 

I have that grounded. It wasn't grounded at the time my starter wasn't working, but I did ground it sometime after I grounded my starter. Should I disconnect the aftermarket ground?

 

I just started it two weeks later with a charged battery and it idled for 5 minutes at around 1500 rpms when it got to 1200 rpms it started struggling and shaking then it died. Now it won't run but it will turnover. Any leads?

 

Pull the plugs and inspect would be my first step.