C/K :: 1997 Silverado Just Cranks Won't Turn Over

I have a 1997 Siverado with a 5.7L,auto trans. The truck has 162,000 miles on it . This it the first problem to come up since buying truck a year ago. All I know about this truck is that old owner took very good care of truck and did all the maintenance every 3,000 miles . He told me that he just replaced fuel pump and battery 1 year ago.

Well I noticed that the starter was dragging so I bought a new OEM, NOT the cheap ones priced at 59.99 . WOW! what a difference,worked like new.

Well 5 days go by and everything seems fine intil driving on freeway about 65 mph my truck seems to have a slight misfire and it did throw a code .

I had the code checked and code was a misfire code. All I did was change spark plugs and clear code. Everything seems fine for about 2 days and the truck starts to feel like it misfired a few times but did not throw a code.

I park my truck over night in my driveway over night,and in the morning I go to start the truck and it just cranks, does not turn over. So I crank over and over again. After a min of cranking ,sounds like starter got jammed ,MADE A clunk noise. I did hear some small back fires in mufflers . So I let it sit for a while and got some starting fluid and sprayed into TB and put everything back together and try again,it just cranks and has small back fires in the mufflers not loud at all.

Now it seems that I may have hurt my new starter . The starter engages and just cranks the engine for 2 seconds and then sounds like the starter motor is not engaged and just spins. I take the starter off to have it tested at local auto parts store . They say starter is in good condition. Pass their test.

So I put starter back on and it does same thing. Now it looks like I have 2 problems now. Do the battery has gotten to low on amps or volts? I can hear the fuel pump come when I turn the key to the on position,and then it turns off 2 or 3 seconds later.