When the problem occurs, if cranks good but won't start, have a helper crank it while you visually check for spark at the spark plugs. If you have spark everywhere, use a gage and check fuel pressure. Also, check for injector pulse. Can you check for applicable trouble codes? You may need to use an obd2 code reader that will work with your year--make--model.

Code p0123 shows up

I put the throttle position sensor still no help ...

When it refuses to start, engine cranking, do you have spark at the plugs? When the problem occurs and it won't start, it will crank, correct?

Hey, you should have checked the circuits at the tps before replacing anything. I'm not sure of your engine litre size, I lookled at 3.9L.

At the connector, the violet wire with white tracer is ref voltage, about 5 volts, key on. The black wire with lite blue tracer is ground. The orange wire is tps signal. You should be able to use digital multimeter on the tps signal wire, key on, Move throttle up and down, see if voltage rises and falls smoothly.

Some possibilities to check as far as insufficient engine power.
fuel injector issues
fuel pressure
ait inlet restriction
restricted exhaust
coolant temp sensor
cam and or crank sensor
ignition and coil circuit
map sensor