Did you ever solve your issue at 3000rpm? Im having a similar problem but mine happens at 3500rpm. No check engine light or stored codes. Im randomly checking things based off the searches Ive done on this site and others.
- Checked and replaced some vacuum lines
- Checked ic piping
- Tps checked
- Cleaned maf
- Plugs wires brand new and in proper order
- Even removed cat to see if it was clogged
This all started happening after I replaced radiator and water pump about a week ago. Any help is appreciated