99 v6 promblems help please

i just got a rebuilt motor in my car not to long ago and promblems are starting to occur my engine light came on and blinks every time im driving at a constant speed... when it blinks it feels like my car gets real sluggish or like slows down a bit but when it stops blinking it picks up???:shakehead it is really fustrating after buying a new motor for my car any thoughts????

Auto Zone and Advance Auto will scan your engine free. Post the codes they give you.

thanks ill do that and post them up tomorrow

alight i got the codes
bbcylinder misfire detected cyl 3
bb secondary air injection system fault
bb secondary air injection system monitor circuit high explanation
bbegr system fault exhaust gas recirculation


any help would b great thanks

I would check the coil on No.3 cylinder. Ohm this coil and check if the reading is different than the other coils on this side. Then Ohm the injectors on this side if the reading is a lot different replace. I have a COP tester coil on plug and an injector tester. You can listen to the injector with a long screwdriver to your ear. Look at the plug sometimes they get cracked by being dropped.
I rebuilt an engine before and one of the valves leaked so do a compression test on No.3 cylinder. The machine shop fixed it and gave me a new gasket.
Fix the miss blank the codes and retest as one code can set another code.