Lisinopril is not listed as dangerous in combination with coke (unlike beta-blockers).
What I suspect is happening in your case is this: the Lisinopril is compensating the hypertensive effect of the coke in some way (maybe by vasodilation), and as a result you have tachychardia. Now tachychardia is better than a hypertension-induced stroke of course, so you shouldn't blame the Lisinopril. But it shows you can't have the best of both worlds with coke and blood pressure drugs. Next time take a lower dose of Lisinopril to see if it helps. On the other hand, you must ask yourself if coke is the drug for you given that you have a history of blood pressure problems (otherwise you wouldn't be on Lisinopril).
In another post I told about the day when I took phentolamine (a hypotensive alpha-blocker) when hitting the pipe. God how my heart raced that time! And when I stopped smoking it didn't get better before quite a long time (over an hour). I sat there, not taking any more tokes, and bom-bom-bom went my heart with a vengence.