give this a try dont remove you alarm but just reconnect you starter signal coming off the alarm.
i had the same problem i would have to rock the car and it would start but after i jumped to alarm
it hasnt done it since so i replaced the alarm. happen to me when the car was on the dyno would not start at all. i reconnect the starter wires and its been good since.

 

Ok update on my starting issue. So after replacing my ignition switch and still getting the same problem I decided to look into my alarm. Sure enough once I disconnected the kill switch off the ignition wire the car fired right up with absolutely no problems. So if you guys have this issue and and aftermarket alarm bypass the kill switch and see if it'll work. That could be your problem. I'm just happy it's fixed and working lol. Only reason it took me so long to figure it out was because I hardly drive my car😁. Anyway hope this helps other members who have the same problem.