Sorry this is such a large post, but it was suggested to me to be as exact as I can so that I don't waste any of your time. I am hoping someone can give me some guidance, I have a friend who has some automotive knowledge who has been helping me, I have a 94 ford ranger (push rod type v6 4.0L with 120K miles) when I bought the vehicle, the previous owner had swapped out the radiator. it had approximately 1 quart of oil, give or take, too much, which I drained. Doubt it matters, but I guess he never replaced the lost tranny fluid, I had to put in 2 1/2 quarts, now the transmission works like a dream. There was no smoke of any kind coming from the exhaust, my friends impression was that someone tried to take good care of it. When I first got it, i felt that it was not firing on all cylinders, extremely rough idle in gear. Since then, I have replaced the muffler, all plugs and wires, there was a small improvement in the smoothness of the idle. The vacuum reading at idle (engine warmed up and in park) was a fairly steady 14in. the needle does not hunt. I also connected the vacuum gauge at the upper intake port where the break booster line connects. It pings randomly/on occasion or what ever you call it when it sounds like it is exploding inside the intake =) .. and am getting (koer code) 137 no other codes or faults detected, the fuel pressure at idle is 32psi ... have not been able to test fuel pressure while driving.. engine pings under load (sometimes) and extremely rough idle in gear.. in park, the idle improves dramatically, the bank2 seemed to stay right around .20 volts and bank 1 varied between .1 and .7, like it is not switching. Nothing has indicated any sign of anti-freeze loss, and have not done a compression test.. Today I seafoamed the intake thru the break booster line, about 4 ozs. put the rest in the gas tank. The first 3 -4 miles it seemed just ok; however, after that It seemed to run very rough, and had no power. Had to floor (wot) it to keep it running, it never stalled, but I expected it. I hope that I did not foul out my plugs..I followed the seafoam directions exactly. I am hoping that I don't have to replace them again. I hate to just throw parts at it and would like to know if there is some way to test a part before I have to buy a new one, I want to thank anyone/everyone in advance, for helping me.