Getting hestation af 5000 rmp

[savedbygrace]

Hey guys i got a problem I have a 91 GT. When i'm driving normal my 5.0 doesn't hesitate, but when i start to floor her and hit 5 grand i get back fires and hesitation. I noticed it on first and second gear and then I stopped. Oh and my car is manual. I have no clue

[silverstangboy]

is it throwing any codes?

how many miles?

[Scut95]

Sounds like a spark issue but it's hard to diagnose a care over the internet. Like silverstang said, are there any codes, any other things it's doing? Is your car modded at all?

[savedbygrace]

how do I find out if it's throwing any codes? I know the check engine light will come on every now and then but then it shuts off. It's wasting a lot a gas too. It has cams but that's all i know.