backfire / sputter. ? in 5th gear and 4th

[geno414]

in first-third gear it pulls hard as ever but when I'm on the freway and I'm in 4, 5 gear I will be at around 3k rpm and I will build boost and I will start to hesatate and pop, back fire and it never did this before I have a cop set up ngk one step colder plugs this is making me very mad can any one help out ?. Thank you.

 

[Soccerguy136]

It is more than likely not an ignition or boost issue or fuel, since you can do a full pull in 3rd and should be hitting full boost at that point.

I would look into your tune.