Car stumbles at constant speed

[Far2right]

Hi. My first post for 87 900 SPG. While driving at steady speed, not accelerating or slowing down the car stumbles. In lower gears it kind of feals like when you are first learning to drive a stick and you don't give it enough gas and the car starts bucking. As soon as I give it more gas it stops and takes off. It does this in all gears but doesn't buck in high gears just stumbles. Runs fine at idle. Any ideas on where I should start would be great.

[Digger]

Could be a dirty throttle body but this sounds more like a good old fashion throttle position sensor problem. The car is 30 years old and if it's got the original sensor just replace the sensor and clean the throttle body before you go looking for anything else.

If the sensor is fairly new and cleaning the throttle body didn't get you running smooth call back and I'll talk you through testing the TPS.

[peva]

I wouldn't guess at TPS. Sounds like ignition to to me. I would try new plugs for a start.

[Far2right]

Thank you for info. I will get a chance to work on it this weekend. Had to work last weekend. I will keep u posted.

[Far2right]

It was Throttle position sensor. Thank you