Where do I start?
 

Meh GF's 2001 Blazer 4x4 4dr 4.3..Rough Idle, Stalls out. 160,000

Codes:
PO135 O2 sensor
PO300 Random multi misfire
PO301 cylinder misfire
PO463 Fuel level sensor
P1380 Misfire detected.

Sell it or fix it?
If I fix it, where and what do I start with first, second...and so on...

Thank you Group!
Tony....

DTC's must be diagnosed & repaired in the order they are retrieved. Here is the flow chart for P0135: https://blazerforum.com/forum/diagno...plained-26610/

After the repair, clear all of the DTC's from memory and perform the General Motors Driving Cycle. If the check engine light stays off after completing the drive cycle, you're done. If it comes on before or during the drive cycle, retrieve the DTC's, diagnose, and repair the first one retrieved, clear the DTC's, and perform the drive cycle again. Repeat the procedure until the check engine light stays off.

Most likely needs a tune-up for the misfires; replace O2 sensors. The fuel level sensor could just be a dirty connection.

Not looking at alot of $$$ here especially compared to the reduction in selling price in current running condition.....assuming there is no body damage or other problems. These Blazers will go for over 300k miles....IF maintained that is.

Do you know any maintenance history?