Check fuse #21 (5A) in the central junction box, it powers the instrument cluster short-term memory and the Keep Alive Memory (KAM) in the PCM--if it is blown the cluster will re-calibrate each time you start the engine. Also the KAM will be cleared if the engine is off for more than 5-7 minutes, losing all of the adaptive learning values accumulated by the PCM.
If the fuse is not blown check the battery voltage while cranking the engine. If it falls below 10.5 V the cluster may act as you describe, if below 10.0 V it will behave as you describe. What this means is that there is a weak/dying cell in the battery, a high load (200+ A) battery test would confirm that...
- 2003 GT, UPR X, FRPP 24lb/h, Magnaflow, PP 70mm TB & plenum, Delta Force tuned,
Steeda UDPs, Ralco flywheel, RAM HDX clutch, 3.73s, 262 rwHP/305 lb-ft.
New ride (7/1/2013) 1998 Mercedes SL500-5.0L 32V VVT 326/347 HP/tq