Engine Mechanical Checks

Check compression. See COMPRESSION under MECHANICAL INSPECTION in BASIC DIAGNOSTIC PROCEDURES - 2.2L ION article.
Check engine mechanical for sticking or leaking valves, worn camshaft lobes, valve timing, worn rocker arms, broken valve springs, excessive oil in combustion chamber or leaking valve seals. See appropriate article in ENGINES.
Check for incorrect basic engine parts. Check the camshaft, cylinder heads, pistons, etc.