I seem to have lost power at WOT going up hills is murder. Sounds like I have a cold air intake on. I cleaned the MAF didn't help much.. The truck idles perfect and my gas mileage is about 22mpg. 200,000 miles

Not sure what it could be any point me in the right direction

 

Any luck on this? I feel a loss too going up hills.

 

Do you guys have stock sized tires?

 

Yes, P195 R70 14. I cleaned the MAF last night and it helped a little, I can now reach 65mph. However, I noticed the thermo never left C today, so if the thermostat is shot then it is possible it's not warming up therefore running on cold mode (open loop).