The MPi 2.4 I4 engine was used in KIA Optima/Sportage, the Hyundai Sonata/Santa fe and many other KIA?Hyundai models... The 2.4L is easier to find than the 2.7L V6... If you chose to go to a different Brand (Hyundai) or model/year you would be best to use the wiring harness' and added pollution plumbing (hoses and sensors) from your Rondo...
I took a 2,7L V6 from an older Hyundai Sonata (2004) and installed it into a 2008 Hyundai Tiburon and it fit and worked just fine... Look at your local "pull-a-part" salvage yard... I got the 2.7L with all the extras (alternator,starter,PS Pump, etc) for around $280... Yes you do have to "pull" it out of the donor car but with some tools and a hoist that they supply you CAN do it... Most PAP yards won't supply the mileage on the car/engine and the odometer can't be read (electronic display and no battery)... BUT look for the "oil change" reminder and also look for a donor with major wreck damage... It had to run at that time to get hit!... and worse case they will allow you to return the engine and get another one if you find a dud... Take a 1/2" breaker bar and some large 1/2" sockets... This will allow you to turn the crank over a couple of rotations to verify that the engine is not locked up... Turn the engine clockwise when doing so...
My family ALL drive rebuilt "salvage" cars... My wife drives a 2014 KIA Optima (54k miles), her 2008 Hyundai Tiburon, I drive my 2016 Chyrsler 200s (43k miles), 2006 Jeep Liberty (124k miles), 1997 Ford Ranger (156k miles),and my 2008 KIA Spectra SX (120k miles)... My son drives a 2008 Hyundai Accent (24k miles), his wife a 2008 KIA Spectra (200k miles !! ), my daughter drives a 2008 Hyundai Sonata (30k miles).... All of these cars are rebuilt "salvage" and not one has a "loan" on them...
I have learned body repair, frame repair, engine and transmission repair/replacements, diagnosing problems, welding, and even some painting... My suppliers are regular salvage yards, pull-a-part yards, Rockauto.com, Ebay (a lot), and over the past 10 years I have bought many tools as it is cheaper to buy the tools than to pay a "dealer's" shop and then you OWN that tool... What you might of had to pay to repair a flubbed attempt will more than be paid for by the successful repair and tools bought on average and you learned something that no one can take away from you!
I'm a 71y old retired Electronic Tech that lost my job(s) because of throw away TVs,DVDs,VCRs, Projection TV, Cameras... I have always repaired my cars so the next logical step was mechanics for me and my family and friends... For the most part I feel like a 20 year old kid by being active...
Well back to the KIA Spectra (200k)... I'm replacing both lower front control arms, lower ball joints, tie rod ends, and wheel bearings/hubs... Paid $186.00 for parts and my labor is free to her... They estimated it would cost her $1400.00... See what I'm getting at ??
If you do decide to replace the engine we are here to help with "problems"...
We have Family in Carbondale northwest of WIlkes Barre, PA
(I'm a moderator here and can "see" your location). I'm west of you in Canton, Ohio (Pro Football HOF)
Enjoy!
Dave