2.0l. What causes it to lose power?

Stop at one of the bigger autoparts stores and they usually will scan for trouble codes, free of charge. That code may point you in right direction. If not get back with that code.

i would go buy a factory o2 sensor cause the aftermarket ones dont work that well anyway and the factory one should have 4 wires and of the same color

General advice:After warming up track the problem:sparkplugs (even new can have the ceramic parts broken/cracked /wiring (after warming up the isolation get's soft,can loose spark power)/ignition coil(s) (gets hot,stop runnig),running reach,fuel pump/fuel pump relay.Best guess:fuel pump mallfunction (low pressure) related,fuel filter cloged/water in the fuel/fuel line cloged/chipped. Cheers,hope u figure it out,let the people know.

Replace the netral safety switch

Have you tried changing the gas filter? It sounds like it is starving for gas.

Did you tape a fuel pressure gauge to the windshield,to see if your really loosing fuel, when it quits.
Did you consider the MAF sensor,TPS Sensor.
The pump won't run if it isn't needed. If the PCM doesn't see a crank signal or other data it needs,it won't keep the pump going.
You may be working on the symptom,not the cause.

there is a pressure feed back sensor going bad all the times
also check the two hoses connected to this sensor for crack or blockage
check the pipe that goes to the egr valve for crack
it won't hurt to pull the egr valve back out to check to see if there is any thing cause the valve to stay open

You may have a blown piston ring, valve seals, valve guides, cracked head gasket or a cracked block, etc... It sounds major though for you to lose power suddenly and have all that smoke...

1-timing on truck is ajusted by ecm,when u moved it u cause cam sensor code because it detected timing was off! 2-o2 sensors has the role of detecting air to fuel ratio coming out of exhaust,sends signal to ecm wich collects data from other sensors from that sets timing for best performance,if ecm detects something wrong in system data it will give engine code,that code will point at problem area,in your case o2 sensors probably detected lean fuel ratio that points to fuel system,blocked fuel filter or fuel pump faillure,elect,circuit damage,hope it helped!

Well this could be in your timing. As cars get some miles on them the timing chain stretches therefore causing you car to lose alot of power.So you may want to have your timing set on this car. Also I had a taurus that had a bad torque converter, and it lost alot of power on hills and under loads, also when i gunned the gas pedal. so try the timing first. Hopefully you dont have a bad head gasket or a cracked head these symptoms you are describing are all signs of head gaskets or blown heads