Hello,

The car is a 2008 Versa now with 145,000 miles. A couple of days ago the car started making a loud whining sound and lost all acceleration. The car then started driving normal until we got it home other than the loud whining.

Today I went out to take a look (hoping it was just the brake switch and not the CVT) and now when you turn the car on it will rev up like normal in park (still whines), but as soon as I attempt to drive it it loses all acceleration and response from the gas peddle. The rpm's stay below 1k and it will just idle along in either drive or reverse, neutral or park. About three weeks ago the car did throw code P1421 Cold Start, but it went off and has not come back on. No SES lights currently.

Does anyone have any idea what this may be or how to troubleshoot? The research I've done is a little conflicting between whether it is the CVT or the throttle body.

We were actually planning on trading the Versa in within the next few weeks for a newer one and this happened, so we are trying to avoid taking it to the dealer or a mechanic at the moment.

Welcome to NICO! Sorry to hear that your car is having trouble right when you're ready for a new one!!

Here at NICO, we have Factory Service Manuals available free to members. Take a peek at the link in my signature and find the FSM for your car and you'll have all the info you'll ever need to make the repair if you haven't done so already! It should also help you get a better idea about what might be wrong.

Yeah I would definitely lean more towards throttle body.
There should be some troubleshooting outlined in the FSM that you could start with... checking voltages at idle and wide open throttle.
You could also try removing the intake tube and looking at the throttle while someone pushes the pedal to see if it opens all the way.