Chevrolet - Venture :: 2001 - Losing Power And Sputtering

I have a 2001 chevy venture (254,000 miles) that has me baffled. It has been a great van but it started about a month ago sputtering and bucking and numerous times shutting off. Most times the engine light would NOT come on. It would get the hiccoughs and start bucking like someone learning to drive a stick shift for the first time. Once it sputtered hard enough to throw off the serpentine belt. I put a new timing belt on it last year when I redone the intake manifold gasket. Now its not shutting off but it has only about half the power it should and the engine light is starting to come on more often.

It bogs down and then it will try to go then bog down again. The engine light blinks for about 20 seconds then stops and goes out. When the engine light is on and stays on the code most often says system too lean, and a egr flow insufficient. It does have a vacuum leak in the hose going to the egr. Have ordered that, hasn't come in yet. Gas mileage is horrible. I have done new plugs, fuel filter and cleaned the K&N air filter. Someone suggested the catalytic converter. I dumped in a bottle of 'Cata-cleanse' from Autozone. No difference. A friend of mine had a venture doing the exact same thing. It was in the shop for 6mo with no luck. But his straightened out on its own and is running good now. I really don't feel like waiting 6mo to see if this will straighten out.