99 model 5.7 v 8 leaks oil from the front of

If it is engine oil leaking, it is coming from either the valve covers, the front seal at the timing cover, or the rear seal. You state that it does not leak when parked, but in most cases, the oil will continue to drip off the engine after shut off, and you will see oil spots on the ground below the car. The location should indicate where to look for the leaking area.

If the leak is not engine oil, it could be transmission fluid, power steering fluid, or even brake fluid. With the engine running, see where the fluid is puddling below the car. This will be a very good indication of where to look for the component that is leaking.

If this has the v6, it's probably the intake manifold gaskets. This is a super common problem with these. You end getting oil in the cooling system and anti-freeze in the oil, they also leak externally when this happens. I would get it looked at/repaired asap or severe engine damage will result. I've had to replace quite a few over the years.

it could be the sensor but it could also be front or rear seal or head gasket. the presure sensor would only leak with it running, normally. some models hade a oil level sensor in the pan, check that as well.
you will need to clean off the engine and check all the way around it. it may not be a bad idea to have a local shop put some dye in your engine and find the leak that way. it could even just be a valve cover gasket

SOUND LIKE FRONT CRANKSHAFT TIMING COVER SEAL OR REAR MAIN OIL SEAL LEAKING START ENGINE LET IT IDLE SEE IF YOU SEE OIL DRIPPING UNDERNEATH CAR LOOK FOR OIL LEAK AT TIMING COVER OR AT REAR OF ENGINE WHERE REAR MAIN SEAL LOCATED. CHECK ON TOP OF ENGINE INTAKE MANIFOLD AREA WHERE OIL PUMP DRIVE GEAR IS.O - RING AT THE OIL PUMP DRIVE GEAR WILL CAUSE LARGE OIL LEAK.OIL PUMP DRIVE GEAR IS LOCATED WHERE THE DISTRIBUTOR USE TO BE LOCATED.KEEP EYE ON OIL LEVEL IN CRANK CASE.KEEP PLENTY ENGINE OIL ON HAND UNTIL YOU FIX.I WOULD FIND LOCATE PROBLEM QUICK AS POSSIBLE BECAUSE OIL LEVEL GET TOO LOW ENGINE WILL SEIZE UP LACK OF OIL..

An easy way to find the leak is to have the motor steam cleaned or gunked, brush on talcum powder where you suspect the leak might be. Start the engine and let it run for a while, turn it off and look. The talcum powder will make the leak immediately obvious.

The Chrysler minivan products all had leaking problems. I have had 5 or 6 different Dodge or Plymouth minivans from 88 to 99. How bad is it. The most common thing is Valve cover leaks. Front and rear seals in the engine leak as well as the oil pan gasket. If its leaking a little bit at a time open the hood and look at the front and rear of the engine. Do you see grease and oil that has gone down the sides of the engine? Do you see a lot of grease on the engine with some clean streaks going through it. You may be able to see where its leaking from. If you know someone that knows what their doing have them change the leaky gasket/s. If not you can probably have it repaired for less than buying another van unless other things are seriously wrong with the van.
Hope this helps... Dale

YES BECAUSE WHEN DRIVE IT YOU ARE PUSHING THE OIL PRESSURE UP ONE SUGESTION IS TRY SOME LUCAS OIL SEAL RECONDITIONER AND LEAK STOP OR STP IT MAY HELP SOME BUT IT LOOKS YOUR GETTING DUE FOR AN OVERHAUL

It sounds like it's actually burning the oil, rather than leaking it then, I'm assuming that your usage is a lot more than the drop you mention. The entire car has 234k on it? (or did you mean just the trans?) With that many miles I wouldnt be surprised if your valves are letting a little oil slip into the combustion chamber. If the usage is bad enough, it may be time for a valve job, or even a rebuild.

it could also be the water pump that is leaking

Usually leaks at the front or back of the engine are from the oil pan. Sometimes you can slow the leak, or possibly stop it, by tightening the small bolts around the perimeter of the oil pan. These are probably 7/16 or 1/2 inch bolts. You didn't go into much detail about what kind of leak you have, so I am assuming it is a very thin puddle of engine oil. If it is automatic transmission oil your car will stop moving eventually.