In the past whenever I bought a used vehicle I gave it a tuneup, or at least checked the plugs etc to see if it needed one so that I would have a base line for starting regular maintenance.
Things to check are ignition as you mentioned, vacuum leaks, and finally fuel delivery.
First thing I'd check is pull the cap to see what condition it is in.
Then a plug or two, glance at vacuum hoses, and then pull diagnostic codes.
Let us know what you find, and if you need any help.
__________________
BroncoJoe19
2006 Alt Fuel Jeep (electric)
'98 windstar 3.8L
'99 Crown Vic 4.6L
'90 Full Size Bronco 5.0L
I'm not a professional mechanic, take my suggestions with a grain of salt, or a cup of coffee 
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