4000 csq won't rev past 5000rpm

[Ben Lamberson]

I bought an '86 4000csq with 173000 miles on it recently. The car will
not rev past 5000 rpm's. At first I taught the tach may just be getting
old but looking in the owners manual shows I should be able to go at
least 10 mph more before hitting any sort of rev limiter. I see on July
27, 1986 there was a Technical Service Bulletin titled Maximum Engine
RPM - Cannot Be Reached. It says that the incorrect ignition distributor
may be installed. When I asked my local dealer if this was possibly the
problem he said there is no way it would have all ready been replaced
with the right one but would check it for me. Instead he gave me a
bottle of injector cleaner. This did not help at all. I have a 5000t
parts car, should I try that distributor in my 4000. Are the compatible?

Any help is greatly appreciated.
Ben Lamberson