Originally Posted by James Karban
Check these three things

-Timing has to be 5 degrees at idle
-NO BOOST LEAKS
-No exhaust leaks

Reset the battery and take the car for a good spin 20 min hard driving and make sure the cat is hot before you do the test.

Do you still have the stock emissions equipment installed? or was it removed during the engine swap


No Boost Leaks, (sorry should have mentioned that).
No apparent Exhaust leaks (although why would that cause the HC failure)
Timing is at 5deg.