Is a pulse pressure of 20 dangerous and should it warrant a trip to the er. Taking Norvasc (amlodipine) and propranolol and have been diagnosed with tachycardia.?

OK. Pulse pressure needs to be evaluated in conjunction with the rest of the vital signs. It seems that a pulse pressure of 20 is ok if you feel ok. There may be som artifact in your measurement.
Yes, ER ASAP. Yes, if your pulse is 20, that's very very low and definitely i suggest you go to the closest er and seek help. Also stop taking both of your blood pressure pills. The dose of your Propranolol is most likely too high and has caused this.