My LS has been quite down on HP lately. She has a hard time going up hills and doesn't accelerate that great anymore. I just got an oil change and put full synthetic in her and cleaned my air filter. Also I put fuel system cleaner in her last oil change. Seems to be no oil leaks from gaskets or anything....what could be going on??? By the way, she sounds fine....little to no knocking but quite a bit of hesitation.

 

Have you changed the fuel filter lately?

 

What year is your car and how many miles. it could just be the spark plugs and old wires.

 

im not sure about the fuel filter.

my car is a 2002 LS and it has about 60,000 miles.

 

I have also been down on MPG....last trip i made i got about 27 MPG....it is usually about 32....

 

Do a good tune up....
Spark plugs and fuel filter......
Also get some throttle body cleaning spray and clean the throttle body out (do this before you change the plugs)
I think you said that you cleaned your air filter. I would go ahead and change it as well.

 

should i worry about new spark plug wires?

 

Most of the newer car cars from mid 90's, the wires will last for about 100,000
Inspect them. If cracked or if they have been rubbing on something then yes I would replace them. If no then NO

 

i saw on a post a while back something about seafoam products....should i do the entire oil, fuel, and air intakesystem clean???

 

Here is something else to think about too

On the older mid to late 90's and early 2000's
The O2 sensor can start to fail without setting codes. But it can effect engine performance. If I can find the article that about 20 sensors I will post it. It is worth reading..... Talks about early o2 sensors vs newer ones of today.