I have a '97 f150, w/a 4.2 that hydro-locked, and was then fixed[new piston&rod, gaskets. No problems with any leaks internally, but the egr system is screwy, and it's throwing trouble codes for the intake and doesn't want to idle corrrectly, and dies in traffic. I've been chasing down vacuum leaks for the year and a half that I've had this truck, I've replaced the EGR, and it's still kattywampus. Any bright ideas would be greatly appreciated and I'm working on almost no budget so I can't just throw parts at the thing and hope.
Tahnk you for any help.

 

Please post the exact numeric codes.

 

Please don't get upset with my attempt to help you.
Basically your not understanding what is happening from the trouble codes.
If they are 171/174 codes, you still have an intake air leak that has shifted the fuel tables Rich. This causes drive-abilty issues.
Since the motor has been changed and worked on you need to recheck the following;
A. Was the correct intake gaskets and hardware used?
B. Is there an air leak from vacuum hoses, Pcv valve, bolts or other sources?
You can confirm these possibilities with a Scanner looking at stored and live data.
If the codes are different , what are they?
Time to stop the year long + of guessing.
Good luck.