Firstly, I am starting to notice on occasion the transmission feels like it is slipping, but when this happens is highly unpredictable. I have tried to duplicate the conditions in which it will slip to try and track down the problem myself but to no avail. So my questions are, How hard will it be to find a rebuild kit for this transmission, how difficult is it to rebuild, and what transmission is in it?
Secondly, I have noticed a 4 mpg loss over the past few months according to the computer. I know any number of things can cause a drop in fuel economy but I am hoping to get some insight here on where I might look first. Obviously if the transmission is slipping that could possibly be the root of my problem, but given the lack of consistency in that slippage I would like to look elsewhere. I have read in other places that these 3.5L V6s are notorious for intake gasket problems, is that true and would it cause my drop in fuel economy? Any other information that you could give me would be greatly appreciated.

The car I am working on is a 99 LHS just like the title says and it has approximately 170,000 miles. I have had to do suspension and brake work on it, the abs control module froze up on me and I just plumbed around it and took it out. Since then the brakes work fine and I dont believe that the brakes or the suspension could account for my loss in fuel economy.

On another note I am also noticing that it has a bit of an attitude starting when it is cold, I doubt there is anything I can do about that but opinions on that are appreciated too.

I am also trying to track down the source of my fan switch not working in the dash but thats an entirely different kind of problem.

 

humm I would HIGHLY not advise u to rebuild your transmission yourself with no prior experience. As for the MPG do your own math don't rely on the computer which is a weighted avg of the whole time the car is running and driving until u reset it.