Mike, try turning over the air cleaner lid as a cheap performance-enhancing mod. You should notice more noise but also much improved breathing. I built a dual-snorkel air cleaner which breathes great, along with a K&N filter, but is quiet as stock and retains the function of the original heated air intake.
The other mod that will really open 'er up is a freer-flowing exhaust. The stock cat and muffler are quite restrictive, not to mention the 1-7/8" exhaust tubing which is too small for a 4-cyl, let alone a V6.
2-1/4" exhaust back of the "wye" will do wonders for midrange and top end while not totally killing the low end response.
This article on the Little V6 that Could is loaded with great performance tips:
http://www.4x4wire.com/tech/60degreeV6/?
Here's a few more good resources for info on the 60 Deg V6:
http://forums.s-series.org/viewforum.php?f=14 (tip: check out the 'sticky' at the top of the page)
http://60degreev6.com/discussion/portal.php
And if you ever decide to treat yourself to an extra-large dollup of power, I have a collection of files on a 3.4 Camaro/Firebird engine swap that'll blow your mind!! Drop me a P.M. with your e-mail address and I'll forward the files to you.
Regarding other issues with the motor, leaky valve covers and leaky distributor O-ring are common. Cheap to fix, just a little Wrenching Time required. Also you may want to check the tightness of your intake manifold bolts, as sometimes they can work loose and this'll dump coolant into the oil. Bad for bearings!
Other foibles are broken exhaust manifold bolts; GM went metal-to-metal on the exhaust manifold-to-head joint. This may or may not have contributed to the tendency to break bolts. Worst part about this fix is just getting the interference out of the way, other than that it's not a super-$$$ fix. My old 2.8 had a few busted bolts and the manifolds never leaked anyway. Aftermarket manifold gaskets are available and I haven't heard of anyone breaking bolts after using them.
If your mileage is down a bit, try renewing the O2 sensor. O2 sensor is the standard GM single-wire one used on lots of V8's too, real cheap on eBay.
If it sounds good, has good oil pressure (30-55 psi at idle, at least 50 above idle), and isn't leaking a lot of oil, probably a darn good motor that'll run for a long time. I ran the living tar out of my old 2.8 Trooper and it's still running strong at over 160K in the hands of my folks. Gotta keep 'em in the family ya know!!
HTH & Cheers..........ed
