I have a 87 b2000 it started losing power, going up hills, changed the fuel filter and and checked the EGR valve all seem good. Then while trying to get it back home one of the three hoses on the side of the air filter housing came lose and power was restored (the middle hose connecting to the exhaust manifold below the catalytic converter.) I replaced the hose and the lack of power problem is back.....and now in the process of troubleshooting on a test run the truck still running bad when the other hose gets a leak and the power is back. It will run like that but the exhaust gas is coming out of that pipe like crazy and very hot.

 

Hey,

one of your converters is clogged..... You are prb running too rich.

Maybe your Oxygen Sensor is bad or you need a new coolant temp sensor or something else in your emmisions system.