Since you did not specify codes I'll throw out some assumptions
I too went through this all summer going crazy
I will assume since car runs fine, no complaints about gas consumptions that the codes will read lean.
When's the last time your O'2s change?
could be the culprit, but before you replace those try the below simple 'cures" beyond all the cleaning of the EGR portss and throttle body etc.
1)Check plastic vacuum lines they crack
2)Sray electronic cleaner (non residue) into you MAF
(pull air filter cover off, spray into the grey hole in the accordian tube). No need to take off the sensor
3) what turned out to be the cause in my case was
tube off of the pCV (heading to the firewall) was cracked and with the engine on would "collapse"
If you here a "sucking" sound around the area of the EGR, probably this tube or one nearby gone
Another potential cause is you intake gaskets, but unless "funny smoke" coming out your tailpipe, probably not them.
