My 2000 Hyundai Elantra is stalling intermintantly as I slow down at stop signs/lights, etc. I have noticed that the speedometer is not working properly.....i.e. when I'm moving at 30 mph the speedo is reading 10 mph ? But no engine lights are present.... I would think that this should cause a speed sensor/throttle sensor/fuel type sensor to activate a light ? Is there a possibility that the computer is bad ? Is the speed sensor external ? and is there a seperate computer for the transmission ?

well change it dear liza.

https://www.youtube.com/watch?v=xzm9urjQbWU

a small rubber vacuum pipe connecting to the injector system / inlet manifold. Sometimes this pipe perishes and allows air to enter thus decreasing the vacuum. The engine then cuts out. It's simple to check and replace the tubing where necessary. You may also notice the engine cutting out when traveling at speed and one suddenly slows down.

First thing I would go after is the speed sensor on the transmission. Have the codes read to make sure. The sensor is on the drivers side. Standing at the fender, look down between the air plenum/filter and the engine and you will see it.

sounds like speedometer cable is gone or the gears between the cable and transmission which makes the reduction for sppedometer if no cable on that year they have a sensor

Hello jillfrommass and thank you for asking your question, on Fixya.

Here is a simple process that will walk you through a few steps that will pinpoint the overheating problem on your 2000 Hyundai Elantra, without even using any tools. It has helped millions of people, and I am certain that it will help you, because I wrote it for people in your exact situation.
How to diagnose your overheating 2000 Hyundai Elantra
Pay close attention to the 'fans' part of the instructions. ;)

Get more great (money saving) tips and tricks about your Hyundai from: twitter.com/acoates23234
*FYI - You can get all repair information about your Hyundai straight from the manufacturer at: hmaservice.com - Sign up is completely free.

Thanks for the vote, and good luck!

When car stalls check for spark, if no spark check crank sensor. If there is a crack in the sensor when heated crack opens and car will stall

First suspicion - TPS (Throttle Position Sensor)

Sounds like it might be either the fuel filter or the fuel pump, cause if you ran the tank down, you probably had sludge in the bottom of the tank that you sucked into the engine, you can try using a fuel system cleaner, you may have sucked sludge into the injectors running it, Zmax sells a fuel system cleaner, or there is one called RUN RIGHT, I would try putting some of that in letting it sit a few min then after it sat a few to soak in and break down the sludge, then start the car up, kick your idle up to around 1500 RPM do not go higher then that cause you will damage the engine, try that and see if that works for you, if not then I is probably the fuel pump or filter.
hope this helps.

your charging system is not working,so your car is working only on batt. power,when batt.gets weak car will cut off! good chance alter nator is defective! check alt.elect. connections at alt,if con.are good its alt.

Here is what you need to do, a cleaning of the intake throttle blade and the idle speed control air-bypass valve, they get full of gunk over the miles and cause idle issues (stalls) like yours,
Get a can of intake cleaner from any local parts store, not carb spray, intake cleaner, it is made by a company called CRC, remove the air intake hose to the engine, hold the engine at idle high so the engine won't stall, then spray the can of cleaner into the intake while keeping the engine running, use at least 1/2 the can, shut down the engine and disconnect the battery for 5 minutes, then restart and complete a number of mixed driving cycles, town, freeway, stop and go etc., after a few days the problem will go away as the system will relearn to the clean intake