[dguinaugh]

I have 88 5.0 gt . I replaced the heads because of bad valve. new cats back. but the first set of cats are getting cherry red in 5 mins or less where should i start it runs good a litttle slogish. no popping. where should i start first. thanks for any help.

[Nyt_Muves]

Originally Posted by dguinaugh

I have 88 5.0 gt . I replaced the heads because of bad valve. new cats back. but the first set of cats are getting cherry red in 5 mins or less where should i start it runs good a litttle slogish. no popping. where should i start first. thanks for any help.

You are burning rich or have plugged cats... on an 88GT if they are original I would bet on the latter or a combo of the two...

[The Greek]

You need to check the condition of the ignition. If the cats on both banks of the engine are getting hot are the plugs firing or are you experiencing multiple misfires? How are the ignition wires. Are you sure that the air injection tubes are hooked up on the back of the cylinder heads. Is there anything not functioning on the air injection (thermactor system)? Any codes being set. How about the O2 sensors?