After reading several of the posts I decided to go ahead and change my air filter. Once under the hood, I noticed the case where the air filter is housed was ajar off the two rubber like washers. I do not know how long it was loose or ajar but I was wondering what type of effect this could cause to performance, etc. I have it secured now again but have not been able to really get it out to notice whether or not there was any loss or not.

 

Well with there not being a good seal the only thing that could have happened is that you sucked dirt directly into the engine.
How often do you check your oil? You should check it no less than everytime you get gas. At that time it is also a good idea to check otherthings, like...the airbox. Brake fluid, belts hoses etc. Just a quick visual, takes maybe 5 min.

 

Knowing which model discovery you have would sure help to visualise what you mean to say.

 

Sorry, its a 95 Disco I. I check the oil every other gas fill, and do a quick inspection of the belts and hoses. Embarrassingly enough, I never took the time to check the airbox.