97 plymouth voyager 237900 kms stalls stop lights runs fine at higher rpm it seems to rich at idle

which engine.??? never post lacking engine ,here is why.
1.3 L G13B I4
1.5 L G15A I4
1.6 L G16B I4
1.8 L J18A I4
1.8 L BP-ZE I4
1.9 L XUD9 diesel I4

Ill answer in the generic and for GAS engines. only.
that is illegal RPM, the ECU regulates it to 800 all the time
that means the ECU can not regulate the RPM now, for many reasons.
and sure it vibrates too low, that is normal for all 4cylinders to do that.
no bad engine mounts never lower RPM to 600, ever.
they dont control idle speed at all.
the #1 reason for most cars to idle too low are:
1: EGR leaks, (clean it)
2: ISC stuck closed (electric idle speed acututor dirty) clean it.
3: gross misfiring , caused by bad spark or bad fuel mix.
4: low compression on 1 or more cylinders (real low) Do compression test at WOT. throttle.

Have you checked base fuel pressure with a gauge ? Have you tested the asd relay ?

mass air flow sensor or air filter stopped up ,,,this on this model is very sensitive.

You may have two different problems.
The rich mixture could be several things including a faulty O2 sensor or leaking injector. If a sensor fails it should set a code in the computer.
The stalling could be a dirty throttle body or a problem with the idle speed control valve.

It sounds like you have changed everything except the most likely cause of your engine idle problem....The Idle Air Control (IAC) It is located in the throttle body and looks like the picture below.


Also, to answer your question, TPS stands for Throttle Position Sensor. It is located in the same place on all cars...On the throttle body. No, it is not likely to cause the symptoms you are describing.

Fuel pressure regulator

This sounds like a fuel problem, I would check the IAS( Idle Air Speed) motor located on the throttle body , possibly a wire problem try wiggling them first to see if it changes the idle speed or stops the surging your referring too ! has a check engine light come on at ant time ?

It sounds like the connection to the cluster is not making good contact.

if it is burning rich, there for it will be over fueling around low rpm i do belive, which will cause the engine to flood, im guessing after you have been low rpm then go for high rpms, it like hesitaes and takes abit of a cough then goes, if that is the case then it is overfueling.

there is a way to advance/****** the engine mixture, but id say for safe if you don't know what your doing to take it do a garage, and ask for it to be timed up with the timing strobe light :) which will stop the, over fuelling around low rpms.

I ran into this problem this past winter and after going threw everything I finally solved this problem by taking off the fast idle servo and cleaning behind it with solvant If it gunks up in their it cannot function properly causing it to stall when idiling or coming to a stop. Try this simple solution it will more than likely work for you and keep it from stalling.