Stumped here fellas just picked up a truck on a good deal didnt run was said it needed a vp so i threw an ho pump on i had laying around got it running after a hard start and some code reading later found out it needed a crank sensor after i got it running but when letting off throttle it chugged bad and ran kind of choppy put one in and it started much better but tach only works when first started then drops out short after and still idles kind of choppy and still chugs bad when letting off throttle in drive didn’t know if there was any common problems i can get more info on it tomorrow as well, thanks in advance to anyone who can help!

Tach signal is dropping out and ECM is in limp mode trying to keep it running. Might try the new sensor. While the sensor is out you might want to check the tone wheel inside to see if it loose on the crank. I've seen one case here on the website where the tone wheel got loose and was tore off the crank.