whenever im driving along in OD, and i am around 70 mph (4th gear) around 2200-2400 RPMs, i get this "surge". the tach will show a "spike" up to about 2700-2800. it lasts for a fraction of a second... but u do feel/hear this small surge. if i stay in the 2200-2400 rpms range it will happen once every 30-40 secs. i dont get any engine codes on the drive, and whe i check, it doesnt show anything. any idea what could cause this?

 

Sounds like the torque converter is unlocking. Could be a solenoid power issue, such as your brake light switch, or a circuit ground issue, or a mechanical problem with the converter.

Check your fluid level for starters.