LPCOKIE

have a r3 2011. as stated above revs kept going down then it stopped. i let it set about two mins. started up fine got about a mile and happened again. got home after that happening three time. checked codes and nothing showed up. car has rebuilt engine with about 4000mile on it. any thoughts? also anyone know of a non dealer mechanic in Oklahoma city

ASH8

No Codes?, strange if your 8 goes into limp home mode it should log DTCs...limp happens for a reason.

Check the usuals, Battery Clamps contacts are clean and tight, grounds under engine bay tight onto inner skirt panel.
Battery condition.?
Spark Plug condition, Wires and Coils?
Fuel, is gas fresh...Tank clean?, so many places where flooding has occurred have gas stations with mud in tanks that are not cleaned out correctly.
They say it is not supposed to happen but it does no matter how good station enviro protocols and seals are.

Is AIR Filter (air cleaner) new?, has Mass Air Flow Sensor ever been cleaned? (sprayed).?

Last if the above all checks off OK, I would disconnect battery, drain residual power by pressing on Brake pedal a few times (10), reconnect battery.

Remember turn Steering Wheel all the way to right and then left (lock to lock), after engine warm up turn engine off with reset Dynamic Stability and Skid Control.
You then should have no CEL or Dash lights.

LPCOKIE

thank you kind sir. did as you suggested and went for about 10min drive , after cool down got a po171 in bank 1.

ASH8

Fuel/Air is too lean, can mean at a guess you may have an airline or vacuum line not connected. ie come off after engine re-build.?

Check your MASS Air Flow or MAF Sensor, is it clean?, is it connected correctly?

https://www.rx8club.com/series-i-tec...oo-lean-78270/