My sedona only does 70 going downhill. any ideas. it only reaches2.5k revs

First thing to do is get underneath and check the linkage, make sure everything is connected.

go to junk yard and get ecm and change out

try checking your crankshaft or tps throttle position sensor it could cause you to lose power at times

follow the possitif from batterie,you automatic come on starter

This needs to go to a dealer for proper diagnosis and testing.

Sounds vacuum related

EGR Valve or vacuum leak

TPS Sensor ?

this could possibly be an air leak, when I say that what I mean is it's possible that you have a vacuum hose come off it's fitting or a damaged hose check all hose's are secure and not split perished or trapped, think back have you done any work in the engine compartment recently if the answer is yes, that's the area to look in, it's so easy to catch a small hose so it becomes disconnected, have you noticed any oil residue on top of the radiator water or water going down and you have to constantly top it up or is their any white smoke coming from the exhaust whilst driving or is the engine boiling water, a the signs relate to a head gasket leak or blown, unfortunately the Kia Sadona, do tend to blow head gaskets not ever body suffers this but the majority do this a caused by the cylinder head warping over a period of time and the head needs to be removed and skimmed.

Good Luck

ve u checked the speed sensor....i am having the same problem with my 2002 kia sedona

be carefull tranny

Possible defective speedo needle stepper motor. This is the little electric motor that moves the speedo needle and turns the mileage counter.