87 V-10 w/ surging idle, poor mileage - Codes 33, 43, 45

[Kevin Strident]

This is a very old problem that I've ignored for some time but since the truck has again become my DD, I'd like to have it running as well as it can.

33 - map sensor out of range, high
43 - knock sensor or electronic spark control circuit fault
45 - oxygen sensor, rich exhaust

All of these codes are probably accurate but I've wasted a lot of money over the years throwing sensors at problems that were caused by other things. The map sensor has probably been replaced at some point. The ESP is an eBay part from many years ago. The O2 sensor is ancient as well.

Is there anything to troubleshoot with these codes or this particular combination or should I just hit RockAuto and spend the $120 to replace this junk?

 

[TexasSilhouette]

Make sure the hose to the MAP sensor is not leaking. Check the throttle body gasket, they are prone to leakage. Depending on where they leak, they can cause a code 33 and 45. 43 may be a side effect of the MAP problem - uncontrolled detonation.
Map sensors can be tested with a handheld vacuum pump and a volt meter.