without the MAF sensor info feeding back to the ECM it will stay in open loop,

When you crank the truck it is in open loop (speed density) until the temp gets above somewhere around 130* then it goes to closed loop and starts using the 02 sensors feed back for adjustments.

leaving the 02 sensors unplug or the MAF sensor unplug with force it to stay in open loop.

Neal

 

 

Need to figure out why it won't run in open loop. Airflow at idle is low, from what I've seen should be around 6.5 to 8 g/s when warm and A/C turned off. What's the manifold pressure at idle? Does it still have the cats on it? Will your scanner read knock retard?
Neal