Genius dealership...

Here it is. 07 hald ton crew. 4.8l 4x4. I had a dual cat back system and didnt like the way it sounded. So now I have cat only dual exaust. I can understand the lean code that comes up. But. Should the check engine light stay on constantly? Also. This is the genius dealership. The service traction contol and stabilitrack light comes on then the same but it says it turned off. Then the rear end slips on the next gear when shifting. The dealership says its a history code and they cant do much about it. Later that week they told me its because I was running E85 in the truck. They didnt understand that I dont use it nor is the truck a flex fuel vehicle. So any advice besides find a new dealership?

Here it is. 07 hald ton crew. 4.8l 4x4. I had a dual cat back system and didnt like the way it sounded. So now I have cat only dual exaust. I can understand the lean code that comes up. But. Should the check engine light stay on constantly? Also. This is the genius dealership. The service traction contol and stabilitrack light comes on then the same but it says it turned off. Then the rear end slips on the next gear when shifting. The dealership says its a history code and they cant do much about it. Later that week they told me its because I was running E85 in the truck. They didnt understand that I dont use it nor is the truck a flex fuel vehicle. So any advice besides find a new dealership?

can you explain that exhaust better...you had one pipe for each side with 2 cat converters now you have one cat converter with two pipes coming out to rear..?

rear diff,,did you replace remove rear cover and change fluid with the proper diff oil ???inspect teeth for cracks damage..

if you want help you must give the DTC to the forum ..can't help without details...unless you have the equiptment and knowledge with the repair manual for your vehicle you really are in trouble with no competent dealership in your area..

trade it in for a FORD..

Good Lord DON'T trade it for a Ford. That's the worst thing you could do.