Check light on

[Ralph Cook <bluesgtar@redrose.net>]

My recently acquired 93 V8Q is running fine except for an intermittent
Check engine light. The Audi goo-roos I take the cars to have blessed
the car anf given me a can of injector cleaner which they say will solve
my problems......I don't want to seem paranoid but this light is still
on during normal driving however it will go out on a long downhill,
under lowest manifold pressure. 
Any ideas??
Ralph Cook
90 V8Q 194,000 Mi
93 V8Q  43,000 Mi