Chasing some ideas. My 2005 diesel rodeo speedo intermittently becomes erratic. I have only had the car for three months and this issue came up about three weeks after getting it. On ocassions the speedo acts like the tacho, as you push down on the accelerated the speedo shoots up like the tacho even if you not moving. As you release your foot from the accelerated the speedo drops back. The car can go for a number of days and be fine, then be an issue for a day, then be normal again. Ideas?

SOURCE: speedo and abs light on bmw 5 series

I've had the same problem twice on my 1999 528. The problem is your ABS module. (Bosch 5.7 to be exact.) The failure mode is temperature sensitive and shows up after driving. To test this, turn off the car, get a can of freeze spray and cool down the module. Inverting a can of compressed air used for computer cleaning works too. Give it a healthy freeze, then start up the car again. If the lights are out, then you know your problem. 
All sorts of things don't work when the module is bad. Speedo, windshield washers only give you one speed, fuel gauge drifts back and forth, cruise control,  check engine lights, airbag lights .... and so on, you get the picture, basically anything connected to the computer. My new (great) mechanic calls this the BMW christmas tree. 
You can either replace the module with a new one from the dealer, very expensive, or get it rebuilt. There are a number of rebuilders out there, so take your pick. I've used ModuleMaster in the past and they've been great. $300 and works like a charm. Google them to find their web site, and good luck. 
db

SOURCE: 2000 VW Jetta V5 accelerator/idling problem

these cars are fitted with a fly by wire accelerator pedal that is controlled electronically by the cars computer it is possible that there is a computer problem or the throttle body ( air intake system )or accelerator pedal is playing up.
it is highly possible that the car is doing exactly what you say it is i recommend you take it back to VW and demand that they take a proper look at it you might have to leve it with them for a couple of days and get a service advisor to drive it home so as they can see the problem ocure.
regardles the cars computer should of thrown a code declaring a fault in the system witch should give the tecs some were to start looking.

good luck with this problem if you have any outher questions let me no

SOURCE: 1997 Cavalier while you driving hesitates and stall

I had to replace my Idle Air Control Valve and Throttle Position Sensor.

SOURCE: 2002 Camry won't accelerate

check throttle position sensor wire chewed up, broken wire or unplugged? check with volt meter mesure the voltage @ throttle positon sensor see if there's voltage goes up/down when u apply/release gas.

SOURCE: VW New Beetle Turbo GLX stalls, transmission problems.

I have a 98 beetle that will stall out when you give it gas from a stop but it has not cut off. I have changed the fuel filter and oxygen sens. the check eng light came on and said the car is running rich but i have no ideal how to fix it could you guys help me out on this thanks.