I have an issue with engine vibration at highway speeds. Starts up around 55 and dies back off around ~75. (I don't think this is a tires issue but I could always be wrong.)
When driving on the highway i start getting a left to right vibration in the engine compartment that can be felt when driving. I normally run 87 octane gas in the Jeep, and after a couple of fuel ups all issues tend to get worse. When I switch to high octane and/or add an injector cleaner like SeaFoam, the engine vibrations calm down and everything starts running smoother. (Why I don't think it's a tire issue.) I've cleaned the throttle body already and that seemed to have a short term improvement.
When I first start up my Jeep in the morning it actually seems to have problems getting into first gear and reverse. It will pause and then super rev over 3k with a jump. I have to accelerate very slowly for it to catch the first couple starts from a dead stop.
Anybody know what could be causing this?