EGR

My CEL was on, so I ran the codes. P0400, no surprise there. Replaced the EGR valve, cleaned the EGR ports and the CEL went off. It came back on with # codes. P0113, P1131 and p1151. replaced the IAT, cleared the codes again. IM gasket leak, replaced gasket. I still Have a "vacuum" leak.... I think. Vacuum hoses checked and none leaking. CEL back on now, rough idle, odd acceleration, stalls, smoking under hood. And the once again dreaded p0400. I was told the EGR vacuum solenoid could be bad. Checked what I was told was the vacuum solenoid. works fine. I am at a loss as to where to go from here. Oh, and white smoke is comming from under hood.