I have a 1988 w150 5.2tbi the rpms surge especially when you put it in gear and it bogs if you try to drive it backfires threw throttle body bad ,will rev up fine I have replaced o2 sensor,tps,temp sensor,air charge sensor,pick up coil,coil,fuel pump ......the air pump,egr,cat converter is eliminated ,I checked the map sensor at idle out put is 4v revs it goes down to about 1.5v ........SOME BODY PLEASE HELP

 

What codes do you have and what is your fuel pressure?

 

just code 33 and 37, which I believe is ac and torque converter ......fuel pressure is 15,and the injectors spray looks good it mostly surges when it heats up or when you put it in gear