Codes P1450, P0401, P0402, P0304

Codes, codes, and more codes. Okay, we got our VSS problem taken care of. Now after thinking that we had everything worked out, this happens. The check engine light was finally off. Then going down the road, it comes back on. I went to Autozone and had the codes read. This is what came up. We just replaced the EGR less than 3 months ago. I don't understand. Any Help would be greatly appreciated!!!

Codes, codes, and more codes. Okay, we got our VSS problem taken care of. Now after thinking that we had everything worked out, this happens. The check engine light was finally off. Then going down the road, it comes back on. I went to Autozone and had the codes read. This is what came up. We just replaced the EGR less than 3 months ago. I don't understand. Any Help would be greatly appreciated!!!

Dang! Got yourself a real winner of a Winnie, here, don't you? I don't see anywhere which engine you have, 3.0 liter or 3.8.

OK...

P0304 is misfire Cylinder #4 typical of an EGR problem as you mentioned.

P0401 EGR Flow Insufficient
P0402 EGR Flow Excessive
P1450 Unable To Bleed Up Fuel Tank Vacuum

The two 400 codes are generally mutually exclusive... normally I'd think maybe a heated oxygen sensor or the PCM is wigging out, but. The 1450 code, which makes me normally think canister purge solenoid (otherwise known as a Vapor Management Valve, VMV), suggests that you might have a problem with applied vacuum.

I'm doing this off memory on a '97 3.8l, so forgive me if I miss a point here. On the 3.8l the EGR solenoid and VMV use the same vacuum source, so I would take a look at that. If you haven't cleaned out your EGR ports in the intake, that could cause your misfire problem and might have something to do with the codes here. I would go over the vacuum diagram and see if there is a small leak somewhere, as well.

Please provide year and engine. The EGR flow codes MAY be the DPFE which is a common failed item

Sorry about that. It is a 98 Windstar, with 3.8 L. We have also replaced the four O2 sensors with Motorcraft sensors a couple of times. HELP! I feel like I keep throwing money down the drain. Thank you!

I think Dngrsone is on-target. A vacuum leak is a good guess ... perhaps large though intermittent. This is one time I would try checking the gas cap.