compression?? odd readings

[Jeff4764]

ok, so i have an 87 n/a, ive explained this problem before... It starts fine when its cold, but once it warms up it has a hard time starting and sometimes wont even start. I was told to check compression so i bought a tester, (didnt remove schrader valve, just held in relief valve) the pulse is are very even steady pulses and all read the same. Heres the problem, its reading 50 psi every time.. But i was told if there steady and even pulses the compression is fine.. can someone give me some insight.. maybe a different problem the compression