When I worked at Saleen we had a 1993 Ford dually P/U with a 460 ci engine.
In 1995 I was driving the dually pulling a new Saleen 351 SR to the Road & Track "fastest car made in America" competition in Stockton TX at the Firestone test track. The dually had lots of low rpm torque but around 3500 rpm it just started giving up & seemed to have a rev limiter set to 4500. Real pain towing up all the hills in AZ & seemed to get worse on the trip back to Long Beach CA. Dually had about 60K miles & fresh oil change when I left so I assumed it had been well maintained & I had never driven it before. When I got back I told the shop foreman how it drove & they finally inspected the air filter, it was the original & had never been touched before. New air filter added about 100 HP!
When the Road & Track magazine test came out I was in a picture with Phil Hill by the Saleen.