check for vacuum leaks regarding the high idle, esp where the pcv valve is. Its not easy to get at either , being in-line and under the intake (at least on every 2.3 lima Ive had theyve been that way) Timing belt & tenstioner always a good idea when you dont know the history of a engine. Sometimes the egr setup on these engines have issues, my ‘88 was awful but the ‘94 has been ok. 4.10’s are a good start but 235/15’s are about the tire size limit with that engine & gearing, if you tow much 225/70’s are the best balance. If you have the head off for any reason-have it magnafluxed, the dual-plug heads seem to crack in the valve seats over time, even if its never been overheated, think its due to lack of material in the casting along with thermal cycling. Overall not a bad engine, if you have alot of hills/upgrades on your commute you’ll find it wont like 5th gear , not sure its any more gph flow but V8 fuel injectors will interchange & work.