I had a previous post on here a couple months ago bout my 92 deville 4.9. Runs great but when i try pressing throttle past half it like almost dies plus a little backfire. If i release the throttle under half it regains all power again and runs fine. I have replaced the following: fuel tank and pump,filter,plugs,air filter and i rodded out the egr tubes and cleaned the butterflys. Carb looks brand new now . I also reset the ecm so the idle would adjust itself accordingly. I'm lost now and no funds to go to a repair shop. Any ideas would be greatly appreciated.