Timing off 25 to 30 BTDC, 2002 Tacoma 2.7L, timing chain seems right

Hello,
I put engine back together after changing head gasket and adjusting valve clearances and noticed the truck was a bit difficult to start cold. It might even bog out if tried to rev right away. Then it stabilizes and revs up fine. Follow up starts are right away like it used to always be. Starts up one 1st key turn for quite a few hours after 1st start. Also, noticed what seemed like just a tad bit less power also. Checked timing and it was and still is at approx 25 to 30 BTDC (the timing light shoots outside the degree ruler on the cover, to the left). Weeks later I opened up the valve cover and put an extension on the #1 cylinder while rotating crank by hand to check piston up and down movement. The pulley notch aligns perfectly with the zero deg mark on the ruler when the extension on the #1 piston is at max. Also, the dots on the back of the cam gears align perfectly when at TDC (also showing zero on the crank pulley). I noticed a noise develop and a mechanic saw it was the brand new OEM tensioner that was not fully extended. He fixed that, but the timing is the same. He said I had put everything right (Im assuming he also checked the crank and cam alignment). No codes thrown as a result.

Any idea what this could be. I don't see how it could be something with the timing chain when manual checking TDC checks out fine with the cam gears. It almost feels as if the computer adjusts after that initial start or something. After just a few seconds of warm up it starts fine , though as mentioned seems like tad bit less power. No codes.

Any help greatly appreciated,
Thanks,
Luis

 

there was a water temp code and after plugging in the unconnected plug on back of engine, it now throws an O2 sensor code. will replace that and report. Timing with timing gun is about 30 btdc, and code reader reads about 15 deg advance timing.