well thanks for all the replies and suggestions..actually I had the CAT changed last year when I had the same problem,I put in an Aftermarket CAT. It looks a little bit smaller than the original..I also had an Supersprint exhaust installed while I was doing the CAT..the problem was solved when I put in the new CAT but now it seems to be coming back..I also had front and rear o2 sensors installed..not sure if the sensors are failing..but no check engine light..

The plugs were changed about 20000 miles ago..the problem is that once on the highway I am ok..i can get decent power its when I have to stop and start moving again that the car feels like a non-turbo four cylinder and can't seem to get moving ..i can feel as if the exhaust had hole or somewhere there is an leak..but can't seem to figure it out..

will a compression test on the car tell me something..

thanks again

Check other sockets too. A2 is engine but A6 is ignition, A1 tranny, etc. Although if codes I think check engine light comes on. Also 850 are very sensitive to their spark plugs. If you got 20-30k on them might need replacement - also dist cap, rotor and take a look at wires!

Good Luck!

If you are losing power only after a long or highway drive - is your catalytic converter partially blocked and getting worse when it heats up?

I saw this in a Toyota belonging to my mother. She never drives long enough to warm the engine thoroughly and it did not show any symptoms for her. I took it out for a long highway run (>1 hour) and it lost power. Her shop drove it a while and diagnosed the problem by putting a temp probe on the cat - replacing the cat cured the problem in her case. It was suggested the original cat was falling apart internally, though we didn't look inside.

Just a thought...