Help: Inconsistent Horse Power in S4

[Dwayne Cosby <dccosby@interlog.com>]

I decided to make a couple of G-tech runs before I install a boost
controller in my S4. I set the vehicle weight at 4000lbs and the G-tech to
measure HP.

Along the same road surface I get HP readings from 220-245 hp (even saw a
261 hp reading last night when it was 15 degrees C). In all cases I was
getting a solid 18-20 PSI of boost running with an IA stage 3 chip. (FWIW
I also have a K&N panel filter.) 

As a reference, I've used this same G-tech in another S4 and got very
consistent HP readings +/- 5 hp.

The car doesn't seem to be pinging and I reset the ECU to make sure it
hadn't learned any bad habits. I'm also running a new set of plugs.

Since I have plenty of boost pressure, I'm thinking it may be the throttle
position sensor - intermittent WOT. Any other alternatives (plug wires,
coil, etc.)?

Any comments or suggestions? Anyone know what a new throttle position
sensor is worth?

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Dwayne Cosby
94 S4