Car stalls

Hi guys! I’m asking this question for my mother who has yet to move into the age of technology. Mom’s car is a 1998 Toyota Avalon. The problem: after approximately 1.5 hours of driving, whenever the road heads downhill, the engine will hesitate and jerk, and act as if is going to stall. When the road levels off, the car behaves like this for a while, then goes back to normal. It doesn’t do this on every hill, but only acts this way when going downhill.

Mom has taken it to various repair facilities, and of course they can’t re-create the problem, nor can they determine the cause of the problem. Any suggestions?


If I had to guess, I’d say she’s buying gas that has some water in it. Probably the cheap gas.
Most fuel filters or mounted on the rail or frame of the car in a horizon position. Water sometimes accumulates in the filter and when she goes down an incline the water enters the gas lines, thru the injectors which causes the bucking, hesitations, jerking, and since its water, the stalls.
Change the fuel filter… sometimes you can pour the contents in a clear plastic container and see the water and sludge collected in the filter. Pour from the (in) side towards the tank.
Buy a can of carb cleaner ($3.00) and spray/clean the throttle body (behind the butterfly valve) and some times the idle air control (IAC)…
This is mainly good preventive maintenace… If the vehicle is stalling at red lights and stop signs
thats generally the time to clean the throttle body.
Try this and see if it helps… The filter probably needs changing anyway. If you shake the filter and pour out the contents…the gas from a regular well maintenanced filter will be almost clear.
Most resemble India ink.
I don’t think its heat related even since you said it mainly happens after 1.5 hours. The filter and carb cleaner should cost under $12.00. Sometimes a heat related problem shows up when under a load…going up the hill not down. In that case you’d check electronics from the module/distributor to spark plugs.