[Shotimes] Intermittent Misfire on '94 w/ATX (long)

[J.B. Hebert]

Hello:

I've been working on a problem with my '94 SHO 3.2 ATX.  It's driving me 
nuts, so I'm hoping that someone here can point me in the right 
direction.  It started a few months ago with a surging/misfire at light 
throttle input.  I thought I might have gotten some bad gas, so I ran a few 
containers of Techron through and the problem seemed to go away.  Then a 
week or two later it came back again.  It felt like one or two cylinders 
were not firing properly.  Following standard troubleshooting for these 
cars, I first checked the spark plug wells.  Sure enough, 2 or 3 were 
nearly full of oil, so I replaced all the valve cover seals and cleaned out 
the spark plug wells thoroughly.  After reassembling the car, the problem 
once again seemed to be resolved.  However, after a few hours of driving it 
returned.  At this point I had my mechanic run a few tests, and he found 
that one of the cylinders was running lean.  I decided to have the 
injectors rebuilt in case I had one intermittently sticking.  At the same 
time I replaced the coil, in case I had one that was failing, as well as 
the air and fuel filters.  I put the new injectors in, and once again 
everything was fine for a while.  Then the problem returned.  At this 
point, I thought it might be a spark issue.  Even though the previous owner 
had recently had the spark plugs and wires replaced, they did not use 
quality wires, so I replaced the spark plugs with the appropriate 
Motorcraft platinums and put a set of Taylor spiral core wires in.  After 
doing this, the car ran great for about 15 minutes.  I took it out on the 
highway and got it warmed up, then did a couple hard acceleration runs.  It 
was running out smoothly and with good power.  However, after the second or 
third run, I noticed that the car wouldn't rev over about 3800 RPM.  It was 
like it was hitting a rev limiter or something when it tried to open the 
secondary runners.  Suddenly, I completely lost power and the tach dropped 
to around 300RPM, even though the engine was still turning much faster than 
that.  I managed to get to the next off ramp and at this point the car was 
running on MAYBE two cylinders.  It would move, but the exhaust note was 
very bad and the transmission was having trouble shifting.  The tach was 
way off; it would read around 400 RPM even after a shift.  Around this time 
the cabin started to fill with nasty, burnt plastic smoke.  I pulled off to 
the side of the road and shut down.  I popped the hood and could not find 
the source of the smoke.  It soon disapated so I started the car, and it 
ran much better.  However, while limping home it got worse again and the 
smoke returned.  I made it home and shut the motor off, coasting down the 
driveway.  Once again I was unable to find the source of the smoke.  One 
last thing to note:  at no time during any of this has the check engine 
light come on.

This car is driving me nuts, and making me long for my '89 MTX.  Does 
anyone have any ideas what might be causing this?

Thanks in advance.

J.B. Hebert