2001 Chevy Van Transmission trouble

I will forward your post to our GM trans tech.Be patient and thank you for using 2Carpros.com

You might want to check the codes again. There is no P1415 code for this vehicle.
The P1870 code is the death code for a transmission. It is a transmission component slipping due to a mechanical failure in the transmission.This means time for a transmission overhaul.
The surging is usually a result of a faulty transmission pressure control solenoid or debris in the valve.

You might be able to extend the life of the transmission a little longer by replacing the pressure control solenoid and flushing the transmission.After that, clear the codes and see if they come back again. I would expect the P1870 code to come back. Sometimes it will take a long time for it to come back due to all of the parameters that have to be met in order for the test to run.
Be sure to get those codes checked again and post the results for me. I'm thinking you might have a P1811 code, since this code is related to surging and harsh shifting.

I got the codes off of the emissions test. and those are the codes it pulled up p1415 and p1870. Autozone said the p1415 was an O2 sensor. What is a trans overhaul and how much would that run. You know just a ballpark figure I can use for my budget to see if I can afford it.

An overhaul is to have the transmission rebuilt.
Prices are different depending on where you live. In my area, it would cost around 1700.00