I have two 89 mojaves. One of them I only need two adjust the valves about every 9 months and the other I am constantly having to adjusts to keep the thing running. Can anyone with experience in this area tell me why this is so and what I can do to fix the problem.

 

I have an older Mojave with DOHC, I'm not sure if the new ones still have that or not. But sounds to me it could be a retainer nut on the rocker arm coming lose. Or if they switched it to a pushrod engine, it could be a bad lifter.

Dunno, best bet might be to just take it to the dealer for a once over.