Bought a 2002 Mazda MPV from an Auto Auction. Looks like someone was murdered in it and runs real rough. Took it to a mechanic. Dude hooks up his computer diagnostic tool to it. Says "random misfire." Pops hood open and unseats cable connection from the middle of the three cylinders. Engine takes a very noticeable "hit". Starts rumbling, etc from the loss of power. Plugs the coil back in and the van returns to "normal". Dude unplugs the cables from the outer cylinders. Engine still runs like it did before, no "hits" taken. Thinking bad coil or spark plug, dude takes out the outer coils/plugs and leaves them sitting on engine. Starts Van and sparks immediately start popping from the plugs. HE SMELLS THE PLUG. "Yup, got gas on it." Getting sparks from the plug, getting gas to the cylinder, I say "maybe there's not pressure." He says "my wife's Ford [something-or-other] was doing the same thing. Getting a new PCM fixed her car, you should do the same."

Ordered a new PCM from eBay for 100 bucks (really don't want to sink more money into this van than I absolutely have to) and installed it yesterday. Van won't start now. Could be I didn't mount the new PCM yet and it needs to be grounded? Could be the PCM needs programming? Help.