95 camaro 3.4l blowen head gasket changed out & timing chain & gears went to start hard to start but starts runs rough when i give gas pops through throttle body also here lifters tapping

recheck the valve timing as it appears that you may be a tooth out on the chain and you have an inlet valve not quite closed . The tapping may be the piston just touching the valve head from the wrong timing

The chain could jump a tooth or two, but normally a chain or gear breaks. You could pull the spark plugs and check compression to find out.
It sounds like one or two injectors may have failed allowing liquid gas to flow into the cylinders.

Changing the plugs probably had nothing to do with it.
White smoke is usually a sign the engine is burning coolant or trans fluid. You might want to check those fluid levels.
If the coolant is low, you may have a leaking head gasket or intake gasket.

get in and have someone put it in gear .give it alittle gas at a time till it starts to cut out and hold it there while you take a test light and ground out each cyl. one at a timeto see if they are all firering

Sometimes white smoke is burning coolant.
Are you loosing any engine fluids ?

Timing chain ,marks right ?

Check your valve adjustment ( rocker arms ).

usually when the camaro runs rough that could be bad fuel injectors-o2sensor and fuel filter-thats my guess i had the same problem and i put bad gas in and the fuel filter went bad

either bad head gaskets,oil pump is bad,start with simple things change oil & filter start car listen to see if you have an air leak around intake and or heads hook an oil compression tester up and see if oil is pumping properly if not could be a faulty oil pump

The 3.4 L engine is problematic. My Camaro started overheating intermittently and my mechanic said he was afraid the head gasket was going. Hoping that it was anything else, I replaced everything in the cooling system from the radiator back. It kept overheating, but not consistently. Some days it ran fine and other days it ran into the red zone before the engine was even warm. And despite not leaking, it was down about a quart of water every time I drove it. Finally, it started running rough and eventually it was undrivable. It was in fact the head gasket -- a common problem with that engine. You can't replace the engine; Chevy doesn't support it any more, there is no crate engine that fits and the cost of replacing the head gasket is close to or exceeds the value of the car, since most mechanics want to drop the engine and tranny out the bottom to get at it. I got lucky and found someone who did the work without droppng the block and had the heads remilled. It still cost over a grand, but I love my car so much that I would have replaced it anyway. I've been driving it for close to two years since then. At 188K, I know it's not going to last forever, but the last gen Camaro is the last beautiful American car and driving it gives me so much pleasure that it's worth it. Good luck.