I have a 1999 3.8 liter camaro that had 87000 miles on it and i blew the engine so i put a identical engine in it with 22000 miles on it. It ran really good and strong for about 3000 miles then one day i was driving it and it started having a loss in power.I pulled off along the road and noticed the cat. converter was glowing orange. It took all it had to make it home.I replaced the cat. and i took it out after wards and still ran like ****! It only will go up to 4500rpms and has hesitation when you give it gas. I checked the fuel filter and it was clean.The car will idle fine but runs awful! My friend pluged a code reader to it and it said multiple misfiring cylinders.I cant take it to a garge due to money purposes. I really need to know with the problem is.