I have a 2006 dodge grand caravan and have been getting code p0404. I replaced the egr, and reset the codes but after about 100 miles, the code came back on. I am beyond frustrated as now I have no clue what to do. Any suggestions?

Go waranty a EGR and put another one in it. Probably got a bad one. or buy a Factory one.
Inspect the EGR connector, make sure it is not mess up.

Did you disconnect the battery for a few minutes while replacing the EGR? I was told this is a necessary step since apparently the ECU stores some corrections table for what it has come to expect from the EGR valve. When you replace a bad one with a good one that table is now way out of whack and needs to be thrown out and I was told unhooking the battery for 5-10 minutes should do that.

No idea if that is true, but I did that when replacing my EGR and I have not had an issue with the codes returning.

I disconnected the battery for 30 minutes after I replaced the egr.

I agree with steak59 a re-replacement I would try first

my 06 threw the same code, replaced the egr valve and it hasn't been back, I too used aftermarket but had no problems

I am also noticing sluggishness when at high rpm to shift and also lack of power going up hills. I am not sure if this is related to the egr or not.

Could this be a plugged cat...? I think it could make a situation where excessive backpressure is causing excessive EGR flow triggering the CEL and the increased backpressure is causing the poor high load/RPM performance.

How many miles on the van?

I suppose an over-opening EGR valve could also cause these issues so don't immediately go replacing the cat, but it might give you something else to check.

My van currently has 76000 miles on it. Taking it to the dealer to get it checked out since it is currently under warranty