My 2000 Tahoe z71 with 5.7 V8 is acting up. Over a 3-4 month period, I've noticed a problem climbing hills in a hurry (like when I get on the parkway). I thought it was the tranny slipping, but when I brought it to my Tranny guy, he gave the Tranny his blessing and indicated the engine was losing power which felt like slipping. As long as I don't "punch it" flooring the accelerator, I can drive it reasonably well - took it on a 5 hour drive to the mountaiuns last weekend. My mechanic suggested the catalytic converter was blocked (I have 170K miles on the car) and I had him replace the "y" pipe last weekend. I picked it up today, still has same problem - In a bit of craziness on my part, I checked to make sure the airfilter didn't look clogged and even drove it a mile or so w/o the filter to see if that would help - no good. If I fllor it, the engine does not rev more that 3000RPM. This may have nothing to do with it, but i hit the reset button on a sensor in the duct from the filter to the carb. Engine now revs well past 3000RPMs as has much more pep, but runs a bit ragged and stalls too. Any ideas?

How many miles on tune up? Plugs and filters and basic tuneup?
Any check engine lights on or flashing?
The reset button is only a air filter condition tester.
Has nothing to do with engine running.

couple of years since tune up - probably 40K miles, noticed filter wasn't seated right, there was a gap in the case when closed - closed correctly now - drove it about 60 miles today - still running rough, particlarly at start, but full power now - thinking about bringing it in for full diagnostic test - no check engine or warning lights on

Good diagnostic check may help.
Also check fuel filter and fuel pressure.
Good luck and let us know how it goes.
MT

I'd suggest a Diagnostic check... I had a somewhat similar problem in my truck - Same Model/Year. Turns out I had over-oiled my K&N Filter and the oil had dripped down and screwed up the Mass Airflow sensor. Mechanic hooked it up, pulled the code and solved the problem.