My '08 Cabrio with 90K+ miles seems to have an engine miss when under load but the check engine light has not come on. Have relied on a diagnostic code in the past, pointing me to a cylinder. Haven't tried to read a code yet, assume one isn't there. Anyone else had an obvious miss that didn't illuminate the check engine lamp? Ready to try a replacement coil or plug or plugwire, but would rather not be guessing, definitely don't want to trouble a dealer to charge me $300 for a diagnostic. Please share any thoughts, thanks in advance.