1995 Chevy Camaro Z28, 350V8, Engine Code "P" (in VIN),
109k miles, no modifications (except for Flowmaster).

Driving Florida to Texas - after about 550 miles of
constant driving (75-80mph), stopping only for gas,
as I was climbing the bridge over the Mississippi
(in Baton Rouge), the car sputtered slightly, then
appeared as if she were running on four cylinders.

The oil pressure reading dropped some and the temp
gauge began to climb past the half-way mark (was
normally hovering just above the 1/4 mark). On the
descent side of the bridge, I coasted off the freeway.
I open the hood and saw nothing out of the ordinary;
I checked the oil and water levels and both are fine.

I decided to let her rest for an hour and then see
how she acted afterwards. Over an hour pass and I
crank her up and she appears to be fine. So I take
off and pass through Lafayette and just shy of Lake
Charles (another 125 miles), she starts to hesitate
again. So I decide to stay the night and try again
during the morning time.

The next morning I start her up and drive on in to
Houston (~150 miles). Just as I get into Houston, she
starts running rough again. I also notice that gas
mileage is rapidly degrading.

If I mash down on the gas, I hear a "wheezing" noise
from under the hood, but goes away when I let up on
the gas pedal and am cruising along. I only hear the
wheezing noise when accelerating. As I've also said,
when I mash on the gas, she has almost no power, with
the strange exception when she gets up around 60-65 MPH
(which I think is around 2500-3000 RPM), then she
"clears up" and runs fine.

I limp home around 3pm and let her rest until the next
day. When I started her up again she seems to be fine
idling, but [now] when I put her in Drive and drive off,
I get this "running on four cylinders" effect, plus the
wheezing noise when I accelerate.

I'm pretty good at troubleshooting pre-computerized cars,
and have done all my own work on all my vehicles, but
this is my first car that is ECU-controlled. My motocycle
(99 Hayabusa) is ECU-controlled and if I am having
problems, I can use a paper-clip to jumper the service
connector and get a numeric readout on the dash to help
diagnose the problem. AAMOF, the motorcycle exhibited very
similar traits and I put a [variable] resistor inline on
the "outside ambient" temperature sensor, to trick the
engine into thinking it was cooler outside. The engine
would run terribly and eventually shutdown, until I made
this modification.

Is there a way I can jumper the service plug on the Z to
get a readout on the dash/etc?   Is there an instrument
I can get to help with this?   I've done some research on
my problem, but I've read conflicting answers, from a
fautly engine-temp sensor to a faulty ECU. How about a
good shop manual for the Z?  Any thoughts on the problems
she is exhibiting?

In my googling, I've also discovered that one of the first
[simple] mods people make to this car, in high-temperature
areas, is to switch to a 160* thermostat and adjust the
ECU to turn the fans on at 160* (versus the 180* factory).
Sounds reasonable to me, unless someone has other thoughts
on this.