First off, I have an 85 camaro Z28 w/ an aftermarket 700R4 that shifts strong (squaks the tires in all shifts) but now wont shift into overdrive and I keep getting lean exhaust, and spark control module error codes. The trans has under 1000 miles on it and not abused, so Im hoping its a sensor issue. The engine is bone stock with the execption of a motorvation chip. I was told from a mechanic that it might be a vaccum leak, but these cars have a million hoses so if it can be narrowed down that would be great. Any help would be amazing!! I want to drive my car before summer is over!!