surging while driving?

[maxwell944]

first off. Hi guys and gals. this is my first post but i have lurked before. im a fleet mechanic and we use vibes religiously. love the lil buggers. anywho heres the low down. its a 2006 vibe, base, auto. 162,258mi. a few months ago it started surging while driving. surging as in going down the road and then accelerating. say cruising at 35 and then punch it. itll downshift and rev and rev and rev and never go anywhere and right around 4500-5k rpm it acts as if it has a burnt clutch though its an auto. the whole car just kinda bucks forward and back in rhythm. throws the code P0420 anf thats it. help please? it woulf be much appreciated.

p.s. sorry if my spelling is funky im doing this on my new phone and the keyboard is huge compared to my last headset

[circuitsmith]

First of all some will point out that p0420 is a cat converter code.
However the cat isn't necessarily bad and even if it were it would not cause a driveability problem.
Is P0420 the only code reported?

I would first do a compression test to make sure the engine is mechanically OK.
Check the fuel pressure.
Check for vacuum leaks. Try temporarily capping off (or pinching with vice grips) the vacuum hoses to the brake booster and PCV valve.
Test fuel pressure.
Has all the routine maintenance been done, plugs etc.?

[theskydivides]

My 2006 has done this since day 1. Usually with the cruise control, but also if I am going up a large hill it will happen...I thought it was normal. I bought it with 14,000 miles on it.

[Zimm]

whenever i hear about surging in 1st gens, i think about the intake manifold gasket issue.

[SeattleJeremy]

Does it only do it when the car is cold?
My car did the same thing, but only when it was cold, I had the intake manifold gasket replaced and it solved the problem.