jerking bucking surging

Hi to all I have a 97 Taurus 3.0 litre with 120,000 miles It has been maintained fairly well.
I have never had any problems, until now. The problem happens once I am up to speed at 30, 40, 50mph
or whatever. If step lightly on the accelerator to maintain that speed, the car repeatedly jerks, bucks, surges, or whatever name you might call it. It is the worst when climbing a hill, but also does it on level roads. If I lay into the gas pedal a little harder, it stops at once, and everything smoothes out. Also if I put the gear selector in the second "D" (not the usual overdrive "D") this problem never happens.
The engine seems smooth, and no service engine light is present. At first I thought maybe the torque converter was malfunctioning, and coming out of its lockup state. But something else is also happening. I am hearing a banging, popping, or rapping sound coming from the left front area. This sound does not always appear when the jerking occurs, in fact I only heard it about 4 or 5 times now. But it started at the exact same time as the jerking problem. The noise is quite noticeable somewhat like a sharp rap. But the noise happens only once. What I mean is it is not a rap rap rap, but just a "rap" It reminds me of the sound of a large stone hitting the windshield, (except more by the engine transmission area). Also to note, this noise DID happen when I had the gear selector in the lower "D" (not overdrive) but the noise happened without the jerking.
Sorry for going into allot of detail here, but I hope it gives some clues.
Please help me to understand what could be wrong. Thanks Mike
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has the transmission ever been serviced?? the bucking sounds like it is "hunting" for overdrive, or the overdrive gear is going bad in the trans. this is why it does not do it in drive, cause you are in direct drive, not overdrive. and the rap noise may be a constant velocity joint in the axle going bad.

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Yes, the fluid and filter were changed about 3 years ago. At that time, the car had about 70,000 miles on it.

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that sounds like the problem. the recomended trans fluid service is every 30-35thousand miles.

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wrote:

Check your subframe mounts. Not sure what years they had this problem, but it used to be quite common for Taurus subframe mounts to let go - the big washers rusted out a bit faster than the rest of the car. Also check the trany fluid - both level, color and smell. Your tranny could very well be bad. It would be in the overdrive section and as such MAY still make a noise when not engaged, without interupting power flow.
--
Posted via a free Usenet account from http://www.teranews.com


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could be the ignition module or plugs/wires.. I had one that drove fine at city but under load up hills it would buck and act like it ran outta power.. ALSO check for vacuum leaks the EGR valve etc.. <clare at snyder dot ontario dot canada> wrote in message

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Just to let the group know what fixed it. A few days after I posted my problem here, I got a service engine soon light. First it was steady, then at times it would flash. The car started to run worse and worse each day. I took it to Advance auto parts, and extracted code P0302. I then erased the code. But it returned right away. After looking around for any obvious problems, I decided to replace the spark plugs and wires. I also added some Chevron Techron heavy duty fuel injector cleaner. Now the car works perfectly again. I guess the sound I heard was coughing, and hesitating. I thank the group for all your help. I hope this may help someone in the future as well.
Thanks again Mike

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