ACFT ENG OVERTEMP WHEN GOING THROUGH INVERSION WHILE RPTR WAS TRYING TO AVOID BALLOONS. THE FLC LEFT THE THRUST SETTING IN TKOF PWR AND THUS THE ENGS ARE LOCKED AND CANNOT ADJUST FOR INVERSION (TEMP) EFFECTS.

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WE DEPARTED COS ON TIME WITH A NORMAL PUSHBACK AND ENG START. WE TAXIED OUT TO RWY 17L WITH AN OAT OF 65 DEGS F AND A TKOF WT OF 112000 LBS. WE ELECTED TO USE MAX THRUST ON TKOF WITH A REDUCED CLB (CLB-2) PRESELECTED IN THE FMC. AS TKOF PWR WAS APPLIED BY THE AUTOTHROTTLES; WE NOTICED CONSIDERABLE 'SEARCHING' BY THE AUTOTHROTTLES. TARGET N1; WAS 97.3 PERCENT AND AN EXCURSION TO 100.7 PERCENT N1; ON THE #2 ENG WAS NOTED AT ONE POINT. THE CAPT PULLED THE THRUST LEVER BACK ON THE #2 ENG AT APPROX 100 KIAS; TO GET IT BACK CLOSE TO 97.3 PERCENT N1; WITH ALL OTHER PARAMETERS BEING NORMAL. WE THEN ROTATED; NOTING SOME HOT AIR BALLOON ACTIVITY ABOUT 2-3 MI OFF THE DEP END OF THE RWY 17L. THE BALLOONS WERE DRIFTING QUITE QUICKLY INTO OUR PATH DUE TO THE STRONGER WINDS ALOFT. WE HAD TO DEVIATE L OF COURSE TO KEEP AN APPROPRIATELY SAFE DISTANCE FROM THE TFC. THIS TFC DICTATED THAT OUR SCAN BE PRIMARILY OUTSIDE THE ACFT. ONCE SAFELY CLR OF TFC; WE THEN RETURNED OUR SCAN TO THE COCKPIT AND NOTICED THAT BOTH ENG OVERTEMP LIGHTS WERE ON WITH A CORRESPONDING EGT ON BOTH ENGS OF APPROX 965 DEGS TO 980 DEGS C. WE IMMEDIATELY SELECTED CLB THRUST (CLB-2) AND CLEANED UP THE ACFT. AS ENG PARAMETERS RETURNED TO NORMAL WE THEN RESUMED A NORMAL CLB OUT TO CRUISE ALT. DURING CLBOUT AND CRUISE WE DILIGENTLY MONITORED ALL ENG PARAMETERS WITH NO ABNORMALITIES NOTED. AFTER DISCUSSING THE EVENT BTWN US; AND GIVEN THE NORMAL INDICATIONS AND OPS OF BOTH ENGS; WE AGREED THAT WE COULD SAFELY COMPLETE THE FLT TO PHX. ALL OTHER PHASES OF FLT WERE UNEVENTFUL. MAINT CTL WAS NOTIFIED PRIOR TO ARR AND THOROUGHLY BRIEFED UPON ARR AT THE GATE. AFTER DISCUSSING THIS EVENT AND COMPARING PRIOR EXPERIENCES; THE LIKELIHOOD OF A TEMP INVERSION WAS VERY LIKELY. THIS WOULD NOT HAVE OCCURRED WHILE THE AUTOTHROTTLES WERE IN 'THROTTLE HOLD' WHERE THE ACFT SERVO MOTORS ARE UNPOWERED. AT THAT TIME THEY WOULD NOT HAVE BEEN ABLE TO RESPOND TO AN INCREASE IN EGT CAUSED BY THE TEMP INVERSION. AS WE WERE LOOKING OUTSIDE TO AVOID THE BALLOON TFC OUR ATTN WAS DIVERTED FROM THE ENG PARAMETERS. THE TEMP INVERSION WAS LATER CONFIRMED BY THE DFDR. WE HAD AN INCREASE OF 8 DEGS IN THE FIRST 1000 FT. BOTH ENGS HAD TO BE REMOVED FROM THE ACFT FOR COMPLETE 'HOT SECTIONS.'