I have a aem wideband guage set up. At about 6000 rpm, the guage goes to lean. This occurs while the motors under load and when the motor is at 0 psi. The set up is 1000cc injectors, and the Bosch setup from Stan. All parts are new. I have used 2 guages and have been throgh 3 sensors. One sensor was old, but I tried 2 other sensors. One sensor worked well for about 2 days. Engine management is AEM. Any ideas of what can be causing the issue. I'm thinking the sensor are malfunctioning, but I could be wrong. Any insight would be helpful. Has anyone experienced this issue.