I have a 01 tacoma with a 2.7 engine and i am having serious power loss problems. This began after a 5 hour trip back from high altitude 10000 feet to sea level. The truck ran good for the trip but started having trouble the next day after about 15 minutes of running. It will idle smoothly and with very slow pressure on the peddle i can get the engine to rev up without missing. If i put it under a load going down even a flat road it will act as though it is going to die. Bad hesitation, hardly any power and a loud vacuum sound comes from the intake. The deaper you put your foot in the peddle the worse it gets. If you maintain even half throttle it will occasionally backfire. At idle or up to about 20 percent throttle if done so gradually the truck will run fine but with more than 20 percent or even normal acceleration speed it will bog out and feel as though it has lost fuel. I only got one code from the computer and it read cylinder 1 lean. The truck has 130k. Any tips would be much appreciated im lost where to go from here. I have a feeling this could be electrical related or fuel delivery. Thanks
What i have done so far
Cleaned throttle body and upper intake.
Cleaned and tested mass air flow sensor.
Replaced spark plugs
Replaced fuel filter
Tested egr valve
Checked all vacuum lines.