I recently had a diagnostic run on my 2000 isuzu trooper after the acceleration started causing some rumbling. The results came back that the ignition coil on cylinder 4 is bad and it needed some new spark plugs. After they attempted to charge me nearly 800 to fix it all i decided to see if i could do it myself. If i order the new coil what steps should i take to begin or is it something that is extremely difficult on this model car? thanks.