My oil light comes on when stopped and goes out with I put on the gas. Doesn't happen every time. I was told it's a 99% chance I need a new oil pressure switch. If so, how difficult and costly is that to be replaces on a 2000 Chrysler.

check the oil level in the sump. Ensure that the idle RPM is at 750rpm or above up to 1000rpm. Check for the correct grade of oil in the engine for you atmospheric temperature.

The oil light coming on when stopped at a stop sign tells me your engine was already damaged before you had the power loss problem. I would not waste the 650 to put in an oil pump. You would be further ahead to just replace the engine.

The proper way to determine what's going on in your engine is to install a temporary (or permanent) mechanical gauge. (yours is electro -mechanical) your oil pressure changes with engine rpm but at idle, it should not drop below 15psi (I don't accept less than 20). The gauge and light is set to come on at a pressure that is just a bit higher than the max low pressure so you have a chance to correct the cause without destroying the engine. (though sometimes even that repair can be expensive).
Since the gauge setup or having someone put a gauge on there costs more than a new sending unit for your current arrangement, I'd suggest you replace the sender and if you see identical readings, then you need to have the oil pan removed and the crankshaft bearings and oil pump looked at.
Doing nothing can cost you an engine.

Okay What it means is that the oil in your car is either low in level or the oil pressure at low revolutions is low. I highly recommend you to stop driving the car when this happen because you can internally damage the engine with a low oil or a low pressure of oil. Check the oil level first..make sure level is fine and oil looks good. Black and burned oil will give you a low oil pressure as well. If it happen that your car need a oil change. Make sure you get it done and see if the problem goes away. Very rarely oils pressure sensor goes bad but if oil is new and level is fine you can take the oil pressure sensor and connect a tester for a oil pressure. If this is not under the manufacturer specifications.. oil pump is worn out and you have to replace it for a new one.
Good luck and don't forget to rte me. Thanks

TIme for an overhaul and rebuild or a new engine. The rings and seals are shot. This is not going to be cheap. IF you keep driving it, there is an outstanding chance that you will seize the engine

When they changed the oil they did not reset the light. The car needs to be told when the oil is changed.

when the warning comes on press the setup button. it should say press reset if new. Press the reset button. It should say if new oil hold reset. Press and hold the reset button until the display changes to oil life set to 100%.

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Turn the key to the on position with the engine off. Push the gas pedal to the floor three times in 5 seconds.

see if you have any oil level or pressure sensors. sometimes these can get gunked up. You may need a new oil pump. I suggest you start using a senthetic oil (valvoline,mobil 1 is reccomended) after u get the problem fixed.

The gas cap is considered part of the emission service and most times a light right after filling the tank is an indication that the gas wasn't replaced tightly. I'd check the gas cap prior to investigating further.

Of course you realize that the pressure fluctuates according to your acceleration right? If it's going lower than it normally did than there can be a compression problem with the engine or possibly the oil pump is putting out a low output.