For two years i've been having issues with my heart racing for no reason. my stress test was negative. should i be concerned?

Heart racing concern: If heart palpitations are your only symptom, most likely you should not be concerned. Common causes would be dehydration, anxiety, intake of stimulants (e.g. caffeine, nicotine, etc.). Another less likely cause would be Wolff-Parkinson-White Syndrome. This would need to be diagnosed with an event monitor. If you are experiencing other symptoms of anxiety, contact your PCP for an evaluation.