check engine light in low rpms

[nickgt5.0]

ever since i got my catback the check engine light comes on when im just crusing at low rpms. why is this

 

[94GTCoupe]

check the 3 hard plastic vacuum lines on the passanger side of the engine.that run from the fender,under the air intake tube, to the engine.if there's a loom covering them,remove that,check for leaks or breaks,fix as needed.

my light used to flash while crusing around 25-35 mph,then go off past that.fixed those broken line's,no more light.this MAY be the problem.i suggest you pull the codes.

 

[HISSIN50]

Agreed. Pull the codes to save time searching.