1999 Blazer LT 4.3, 4x4, 4 door. Recently blew an intake gasket, replaced gasket with the upgraded version and all is good there. After the repairs I now have an issue with what seems to be timing during cranking, when starting the engine it acts as though it's out of time. It will start after a few noisy cranks and upon starting runs perfectly idles good at 600 rpm, no hesitation at all at slow or highway speeds. This truck has always started with a single click of the key even on the coldest mornings this issue only started after the repairs to the intake gaskets was complete.

I followed all guides as to marking, removal and replacement of the distributor as well as replaced rotor and cap while I was in there. Timing seems to be perfect once started but not while cranking, I'm leaning towards cam position sensor but wanted to get other opinions before moving forward with that as I don't understand why I it would be bad after the repair to the intake gaskets when it was previously fine.

Any and all info in regards to this issue would be greatly appreciated, I thank you very much in advance for any assistance.