Jet Valves

This is a carbureted intake manifold shown below.  The throttlebody injection intake manifold has the jet passage located under the throttle plate where both an air/fuel mixture and/or a fuel lean mixture drawn from the crankcase through the pcv valve can pass on into the combustion chamber through the jet valve.

Here's what they look like

These are used valves, if your engine burns allot oil or has very high miles the carbon build-up could be excessive on the tips and the fuel residue collected on the stems can cause them to stick open but its take a neglected poorly running engine that cause this over time.  The springs are held on with small keepers like your intake/exhaust valves.  

Disassemble and clean

The valve you can clean on a wire wheel and the seals are just miniature versions of the intake and exhaust valve seals, the o-rings fit into a groove

Reassemble

Most gasket kits include new seals and o-rings so you can do this

BURNED JET VALVES On Chrysler (Mitsubishi) 2.6L Engines

The AERA Technical Committee offers the following consideration for Chrysler 2.6L engines with repeated jet valve burning problems. This problem is most prevalent with engines that utilize hydraulic lash compensators (HLC). Reported failures have usually been shortly after cylinder head installation or compensators replacement.
Unless the jet valves are readjusted after the engine has reached operating temperature, improper clearances WILL result.

The correct lash adjustment of .010 (.254mm) can only be achieved of the HLC plunger is in its operating location. If the jet valve is adjusted before that point, or on the bench, operating oil pressure will change the previous clearance. Insufficient clearance may hold the jet valve off the seat and eventually burn it.

The AERA Technical Committee