I read all the archived stuff but nothin sounded exactly like mine so here it goes. Im drivin a 1998 Civic HX and for some screwed up reason when im in gear, (any gear) and go above 4k she starts studderin like hell. When im in neutral and rev to and above 4k shes perfectly fine. I love my car, please help!

 

sounds like ecu is going into limp mode u throwing any codeS?

 

the only code is for my primary O2 sensor, I've neglected to replace it for a while but I haven't been driving it anyway cause of the studder. I'm not a mechanic, what's "limp mode"?