Brief History: Received a Check Engine Light. Blindly replaced the EGR and spark plugs. Light still on. Checked the vacuum system for leaks and operation including the EGR position and the EGR solenoid valve. Check engine light remained on. (acutally the light is off when I first start the truck then comes on shortly thereafter.) I then purchased a hand held sensor to read the codes. I received 122 with the KOEO test and received 122 and 998 with the KOER test. The manual that came with the code reader said the 998 code required the KOEO fault to be repaired before continuing.

I checked the wiring to and from the TPS and they look okay. I will check the throttle plates for carbon.

As background, the mileage is 130,000.

Many thanks for your assistance!