This is my first time posting, so bear with me... I have a '94 Ranger 4.0, and have been having some strange issues. At random times, often when accelerating heavily such as when getting on the highway, the check engine light comes on briefly, then turns off a minute or so later. I drive roughly an hour to work each day, and it usually occurs between 1 and 5 times per trip. I also have noticed a ticking when accelerating under load (i.e. going up hill). I have been putting in 93 octane gas to reduce the ticking, but it isn't going away. I also had problems where it wouldn't always start, which I traced back to the EEC relay which I replaced about a week ago. I had been hoping that replacing that relay would have fixed the other issues as well, but I guess that was just wishful thinking. So I hooked up my code reader today, and got a bunch of codes off of the continuous memory check, and no cods off of KOEO or KOER. The codes I got were: 157 158 181 186 189 543 556 I have found the definitions for all of these codes, but most of them don't really mean much to me, so I was hoping someone may have some knowledge of problems that could cause one or more of these codes, so I have somewhere to start. Any help would be greatly appreciated! Thanks.