Ever since I bought my 91 Camaro RS 305 TBI automatic...the service engine soon light comes on while I'm on the highway going over 65 mph. it never goes on unless I'm going atleast 65. I replaced the o2 sensor and EGR valve....and for some time after I did each of those....it didn't come on. I'd say it comes on 40% of the time now when I'm going over 65. Once it comes on.....it doesn't turn off no matter how fast I go, unless I turn the car off. Does anyone have any ideas? because I don't really have the time or the money to take it to the shop to get the codes read. Thanks a lot

 

pull some codes for us plz

 

my car does this same thing. check the egr solonoid. and vacuum lines.