1993 Amigo wont run
 

So I bought a 1993 Amigo with the 2.3L. It ran fine, Then I let my dad drive it. He said that it was running a bit rough and blowing out smoke on the take off. So I changed the sparkplugs hoping that this was the problem. Upon completion of the change I noticed that it was leaking oil into my exhaust. I then conducted a compression check. They all ran at 140 give or take a few. So I presumed that it had to be coming through the valve stem seals. So after replacing them It now will not start. AT ALL. And it is backfiring. I did nothing to the timing as far as I know, I replaced the smog and all of the vacume lines (that I remember taking off). Any one have any Ideas on what the heck I did to her? I really dont want to take her over to a shop as I bought it for my sister (16 years old), and It will end up totaled eventually anyway.:D