i have a 98 se mtx it did this for a while and when i put the dual exh on the prob went away whola go get a dual exh and prob fixed

98 se mtx
k&n air filter custom short shifter
intake res removed
SVT Exhaust shoshop off road ypipe
svt clutch pres. plate ,flywheel, and trans
SVT gauges
SVT front bumper
SVT wheels
fogs /parking

airbox baffles removed