Please help truck has started missing and hesitating when accelerating normally. If you floor it, it straightens up and seems to have no loss in power. Had multiple codes for low o2 sensor voltage and one for random missfires. Yes i accidently lost the actual codes thought my scanner would store them. Because of all the o2 codes i did a live scan of truck when cold just to see what the 4 02s read and 3 read 250 and up while 1 read 0. I disconnected that one to give comp null value and it changed nothing while driving. Did some research and found a tip on possible map sensor not setting codes. It said to disconnect the map and see if truck ran better if it did change it. So i did and it ran like a champ so i changed the map and it fixed nothing possibly made it worse. Ran a system test and all were ok but 3 test $04 id 20 was hi and test $07 id 0c & 0d were hi. These tests are for steady state catalyst 1, no egr intrusive idle test maf out of range hi, and egr decel test. Can someone explain why disconnecting the map makes it run right and any ideas on possible fixes. I have ideas but need feedback before dropping money into multiple high dollar sensors. Please help i like working on cars and consider myself pretty good at it but this computer stuff drives me crazy.

 

the manifold absolute presure sensor tells the pcm the intake presure if you unplug this sensor it will set the computer to default and run off preset calibrations instead of live sensor feed so here is what is likely vacuum leaks clogged cat would both make the map sensor read high or low also the distributors in these are junk and will make them act up but sense the distributors main function is to time the injectors and the pcm has a default setup it will continue to run but hesitate and surge ect.

 

im haven almost the same problem with my blazer it missfires when cold then ill restart it after an hr or so after iv drivin it and it runs perfect i cant figure this one out for the life of me