Engine Surging at Cruise

[FlashFyre]

Long time viper owner. Picked up a 99 GTS last fall. Engine surges in 5/6th gear between 1500-2000 RPM. Wont surge when in 4th gear in similar RPMs.

Any idea on what to look at?

[dave6666]

TPS and MAP will not be the same given similar RPMs in the different gears. Both are cheap and simple to change. O2 sensors are also something to think about if they are original. It is preferred to use OEM if you decide to replace them. Bosch IS NOT OEM. Also consider a PCM reset to erase whatever the car has learned over the last 22 years. What is your volt gauge reading at cruising speed? Do you have cats? How old are them?

[FlashFyre]

TPS and MAP will not be the same given similar RPMs in the different gears. Both are cheap and simple to change. O2 sensors are also something to think about if they are original. It is preferred to use OEM if you decide to replace them. Bosch IS NOT OEM. Also consider a PCM reset to erase whatever the car has learned over the last 22 years. What is your volt gauge reading at cruising speed? Do you have cats? How old are them?

Ill try changing the TPS and MAP to start.

Its got a full exhaust I believe 02 sensors have been replaced within the last 5 years. Its got low mileage 13000. I believe the cats were cut in half. Dont know if they were hollowed out. Definitely smells like it.

I'll get the volts next time im out driving.