VW Passat stumbles while driving

I have a 99 VW Passat that stumbles while driving. It usually happens while we are slowing down or speeding up, but it does happen while crusing at 65 - 70 MPH. We replaced the fuel pump, the spark plugs and the valve cover gaskets. It may run fine, then start to stumble like the classic fuel pump failure. Can you help?:banghead:

what engine and trans do you have?

It is a V6 2.8 with a 5 speed automatic transmission.

I have 1.8T, had similar problem. It came up to be the air intake came off. Check if you have the air intake tight and nothing is there--change air filter too.

I dont usually see drivability issues with V6. How many miles do you have, a worn stretched timing belt can cause driveability issues with no check engine light. It should be replaced every 90-100k miles.

It had about 75K. It only does the stumble occasionally. Usually when it is started for the first time for the day, it runs great. It seems to have this problem after 30 minutes or so. Can a timing belt make it behave like this?

I would reccomend a tune up and fuel filter

I had the timing belt changed and the spark plug wires changed. It runs good now except that it smokes. The mechanic said there was a ball bearing on the block that was crimped on and it was leaking.

There is a water pump thats runs off the timing belt, they commonly leak coolant and if it Was leaking i dont know why the shop wouldnt have said anything because to replace to needto remove the timing belt

Sorry - I meant an oil eak. It seems to be leaking onto a tailpipe or something.

Where does it smokes from: tail pipe or engine compartment?

Also, I am not familiar with mechanics of vw engine, but there should be a rotary seal on any bearing connected to the body that keeps an oil in the engine.

It was smoking from the engine compartment. At first a lot then a little. NOW, the automatic headlights do not work, the turn signals do not work, the AC won't blow. Seems like either the dimmer switch, the light switch or a relay. Maybe that is what I smelled - a relay burning.

vw has LOTS of problems with valve cover gaskets and cam seals especially on v6 engines! they tend to leak onto the catalytic converter.. and smoke alot