99 blaz code 300,1345, 341

Im getting code 300 mult misfire and 1345 cam to crank position correlation fault as well as 341 cam sansorcircuit range / performance. I think it is my CMP sensor but what are the odds of my timing chain being off. I don't hear major noise but it won't start and chugs when it tries to run. I feel compression when I turn it over by hand. Any Suggestions 99 blazer with a 4.3 113k miles. Well it wasn't the CMP sensor or the CKP sensor. I just took off the timing chain cover and the marks seem to line up like they are supposed to on TDC #4 compression. Any ideas?

Cam sensor is in the distributor so could be just that, a bad sensor. Cam sensor is designed to allow start but may run rough. Crank sensor will cause no run and is on the bottom near the timing chain cover and feeds computer with crank data. I attached a P0300 info site for you. 1345 is new to me.
http://www.obd-codes.com/trouble_codes/generic/p0300-random-multiple-cylinder-misfire-detected.php

Well it's not the CMP or CKP sensor and the timing seems to be fine. I took off the cover and the marks line up on the gears on TDC #4 compression.
???? My friend says he was gunning it while passing and now it won't start and rumbles and diesels when it tries to start