Please help me to start solving my problem, I did not find the answer by searching.
Sometimes when I drive with constant speed ( like 50-60 mph), and don't move my right feet, the car starts to accelerate and back. Like when I push the throttle pedal down a little, and back in between 1 sec. Usually it happen at 10 min. after cold starts. Later, and when the engine is warm, there is no problem.
I never have this problem when I accelerate, only at constant speed. I cleaned the MAF, and checked air leaks. Sometimes I got p0430, but not then, when the car is acting like wild horse.
Throttle?

 

The engine pulls and back, pulls and back in short time, like when someone playing with throttle.

 

No clue, but if since nobody answered you I will guess and suggest checking the spring under the accelerator pedal for sufficient tension, as well as the throttle-cable wire for slack/fraying or catching on something enroute to the throttle-body.

Also, if it is at highway speeds, check the full-load breather hose for air leaks (that would potentially do what you are describer as the air/fuel mix would be fluctuating when it shouldn't.)

 

And run a bottle of SeaFoam or Gumout's Best through a tank of gas: dirty injectors will cause a surging . . .

 

Thank you guys! I checked air leaks, and the throttle's pedal, wire, spring.., but all are ok. Next week I will have a longer trip to try the seafoam.

 

Maybe the problem has solved. I used three cans "degummer" fluid in the tank, and i did not got the problem for a week. Thanks for the idea!

 

Interesting what happens when the injectors fitfully spit instead a clean stream. Worst I ever saw was in my 88 325IS: idled roughly, surged (until North of 2000 rpm), but would clean up with Gumout or Lucas (I now think SeaFoam is best of breed).