problems again

[2002 v6 camaro charged]

Well got the car running good for about a week and now I have new problems.
2 days ago I noticed my long term fuel trims were starting to go lean again and then rich on both banks. For example yesterday mroning when I started the car the fuel trims were -2.3% and then the longer I drove the trims were about 2.3% lean, when I left for lunch the fuel trims were 6% lean, when I left to go home they started out at -23% rich and were about 4% rich by the time I got home. This morning when I started the car the fuel trims were 19.5% lean and they slowly went down to 7% by the time I got to work. This morning I also threw the p0420 cat low efficency.
I just changed my CAT last summer, would a bad CAT cause my fuel trims to do this or is it a dummy code caused from something else?
When my EGR was leaking vacuum at the intake I never threw that code and my short and long term fuel trims were at a constant 19.5% lean.
If I had another vacuum leak wouldn't the trims stay lean constantly?

[wezeles]

ya a vacume leak if bad enough would cause it to stay lean but sometimes the computer will try to adjust for it being lean and make it far to rich as well... but i dont know with the numbers your showing it would have to be a pretty bad vacume leak... go to an autoparts store and just buy a reel of vacume line and replace all of them i would say cheep way to eliminate that being the problem... where are you running your sensor from for the numbers? before or after the cat? i put a high flow cat on mine couple years ago and was running my a/f ratio gauge on the o2 after the cat and it gave me messed up numbers because of that cat... make sure its running on a sensor before the cat before you jump to anything...

[2002 v6 camaro charged]

Those fuel trim numbers are from HP tuners. I have a wideband O2 right before the CAT also.

[wezeles]

hmm... are you pretty sure you have a vacume leak somewhere? i know alot of gm's v-6 enignes had bad intake vacume leaks the cheep rubber connectors into the intakes themself never stay tight for long.. i tossed some silicone on mine to make sure they held...the lines themself are cheep and wear out fast from the factory but both are cheep fixes... you should notice it in the idle though..not really so much when driving.. the idle would be sparatic going up and down... maybe look for when you start, normally it will shoot way up the normall start rpm and slowly go down as the computer adjust for it...