Hiccup at 4000 rpm

[jmhibbitts1]

Help!,
I have a 2001 Corvette convertible. The engine runs great up until 4000 rpm. At that point, the engine hesitates between 3800-4000 rpm, then it immediately smooths out and continues to run fine to 6000.
What could be the problem?
Thanks!
John H.

[patsy1]

my 99 Z28 did the same thing i had the maf cleaned and it needed two up stream o2s