91 r/s starts,runs great,then rpm's bounce (bump,bump,bumping)high&low quickly then service engine soon lights go on,then car shuts off.all eletricals work,try &start it,starts shuts off,then starts stays running.drive down road running good,then(rpm's bump,bump.shuts off??

There may be a problem with the electrical connections to the transmission and/or vehicle speed sensor, remove all connectors and check for damaged wires and corrosion. Make sure not to break any connector locks.

fuel issue possibly MAP sensor or tps sensor? any check engine light?? transmission not shifting??

Have a load test done on the battery as the glo-plugs should get very hot very quickly. Diesel engines have to have a high rpm crank speed or they will not start and will leave unburnt fuel in the cylinders ( wet glo- plugs). Every indication is that the battery is flat or is not the right capacity for the car.

you have got to be talking about a diesel engine and its a override protection on diesel engines if you are trying to stay cool or warm in the winter or summers months just bump up th rpm with the cruise control switch and it will be fine if there is low oil or coolant problem top off and you should be fine if not you will need to take to a service center to be repaired

Check out related help links to troubleshoot these problem:----Click the link below:---Idles Fine but RPM jumps in drive mode? http://technoanswers.blogspot.in/2012/07/idles-fine-but-rpm-jumps-in-drive-mode.html
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http://schematicsdiagram.blogspot.com/2011/12/how-to-adjust-rpm-on-2009-dodge-charger.html
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Engine cuts out at 3000 RPM? http://schematicsdiagram.blogspot.com/2011/12/engine-cuts-out-at-3000-rpm.html

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Cold start problem and vehicle shudder around 2500 to 3500 rpms
http://repairhelpcenter.blogspot.com/2012/10/cold-start-problem-and-vehicle-shudder.html

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Cruise Control stops working, Excessive cranks to start the engine and RPM goes max 2500 http://whoisbyme.blogspot.in/2012/07/cruise-control-stops-workingexcessive.html

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1990 Toyota 4Runner: Engine cuts off when reaches 2000 RPM?

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http://whatisbyme.blogspot.in/2012/05/1999-toyota-camry-erratic-stalling-and.html

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These will help.
Thanks.

Check out related help links to troubleshoot these problem:----Click the link below:---Idles Fine but RPM jumps in drive mode?http://technoanswers.blogspot.in/2012/07/idles-fine-but-rpm-jumps-in-drive-mode.html
---------Mitsubishi Lancer rpm needle bounces?http://technoanswers.blogspot.in/2012/02/mitsubishi-lancer-rpm-needle-bounces.html
--------How to adjust rpm on 2009 dodge charger SRT8?

http://schematicsdiagram.blogspot.com/2011/12/how-to-adjust-rpm-on-2009-dodge-charger.html
---------
Engine cuts out at 3000 RPM?http://schematicsdiagram.blogspot.com/2011/12/engine-cuts-out-at-3000-rpm.html

---------

Cold start problem and vehicle shudder around 2500 to 3500 rpms
http://repairhelpcenter.blogspot.com/2012/10/cold-start-problem-and-vehicle-shudder.html

---------
High rpm in neutral? Inconsistant high RPM in neutral?http://technoanswers.blogspot.in/2012/02/high-rpm-in-neutral-inconsistant-high.html

-----------
Jetski Sputters and Low RPM? http://whatisbyme.blogspot.in/2012/07/jetski-sputters-and-low-rpm.html

--------
Fuel Injection Problem And RPM suddenly increaseshttp://whatisbyme.blogspot.in/2012/07/fuel-injection-problem-and-rpm-suddenly.html

----------
2005 Toyota Highlander: Engine runs hard RPM below 3000?http://whatisbyme.blogspot.in/2012/05/2005-toyota-highlander-engine-runs-hard.html

---------
1987 Toyota Camry: RPM Drops going Up hills?http://whatisbyme.blogspot.in/2012/05/1987-toyota-camry-rpm-drops-going-up.html

-----------
Cruise Control stops working, Excessive cranks to start the engine and RPM goes max 2500 http://whoisbyme.blogspot.in/2012/07/cruise-control-stops-workingexcessive.html

----------
1990 Toyota 4Runner: Engine cuts off when reaches 2000 RPM?

http://whatisbyme.blogspot.in/2012/05/1990-toyota-4runner-engine-cuts-off.html

------------
1999 Toyota Camry: Erratic stalling and high engine RPM at idle?

http://whatisbyme.blogspot.in/2012/05/1999-toyota-camry-erratic-stalling-and.html

---------
1995 Toyota LS: Misfire at idle or low RPMhttp://whatisbyme.blogspot.in/2012/04/1995-toyota-ls-misfire-at-idle-or-low.html

-----------
Lexus RX: Tapping noise under Valve Cover At Low RPM?http://technoanswers.blogspot.in/2012/04/lexus-rx-tapping-noise-under-valve.html

----------
These will help.
Thanks.

Well don,t hit bumps then,Check that all the spark plugs wires are on tightly.

I would need to hear the noise to diagnose the possible cause.

white smoke out of the exhaust would be a sign that it is burning coolant... if it goes away after it warms up, it could just be condensation inside the exhaust pipe. 1800 rpm is a very high idle, maybe have your IAC motor on the throttle body checked... check engine light? if so have the code read at your local auto zone.

I feel the codes may be the answer here, idle should be around 8-900 rpm. There are a lot of possibilities for this kind of issue and the codes would be a great place to start.