It doesn't do it under heavy acceleration. Only at a constant speed or with slight acceleration. What would be the easiest and cheapest way to find out exactly what is going on? Also, does the computer record codes even if they don't create a check engine light or an error message on the dash info center?

This is totally what I am experiencing on my bonni.Exactly to the tee!

I have tried everything even having the tcc checked out but no one and I mean no one can find out why I am having this problem seems like a occuring problem with alot of bonni owners.

I have changed the spark plugs,wires,egr valve,coils,o2..both..,Had the fuel pressure checked,did the boost bypass to no avail and switched it back to normal,had the trans checked,had the pcm scaned,god I think I covered everything to check but still the chugging going up hills at a steady speed,I even changed the cat to no avail.

I have just learned to ignore the problem and figured it is normal operation just like gm said to me...I have been to 3 gm shops and they say nothing is wrong so I figure gm knows there cars so this must be normal....YA right!

I sure would like to know why this happens to our cars and how to fix it!