My 85 v6 is acting rather strangely. If it has been sitting for a while (at least a day or two) it will fire up almost immidiately, however if I let it run awhile and then try and start it again later, it takes a lot longer to start up. After enough time it will start dying for a second or 2 at a time and then eventually dies all the way. Once it dies all the way I have to wait a day or 2 before I can start it again. I have had all kinds of distributor and EGR problems in the past that I believe I have taken care of now. Since the engine runs fine when its warm as long as it hasn't been running long I ruled out fuel and electrical problems. I noticed though that I'm getting almost no exhaust coming out my tailpipes. At one point in time I had exhaust coming OUT of my air Intake. I imagine exhaust build up is probably the cause of all this, but what could be causing this buildup?

A clogged catalytic converter. I think exhaust back pressure should be @ 2 or 3 lbs.

Clogged CAT alright. If you don't need it for e-testing, junk it. BTW, for good hp you don't want backpressure. There have been alot of discussion for and against, however, when I went from a racing muffler to a 3 chamber, I lost hp and torque noticably. I then went back to a flow thru type muffler, with lesson learned.

Arn

You might check the coil. A common symptom of coil failure is running fine until the coil gets hot, then it will start to miss and spit, then soon die alltogether, then when it cools it will start fine. Theres no real test for this other than swapping in a known good one.

Definately check your ignition system. If that checks out, then to check your cat, just remove the O2 sensor from the pipe and run it and see if it still does it. This will set a code and don't drive it, but just let it run. If the car runs better after, your cat is clogged.

quote Originally posted by afRaceR: Definately check your ignition system. If that checks out, then to check your cat, just remove the O2 sensor from the pipe and run it and see if it still does it. This will set a code and don't drive it, but just let it run. If the car runs better after, your cat is clogged.

Ditto, Good info by afRaceR, exhaust will come fyling out that little hole, more then you could imagine, you don`t want to stay near it for any period of time,or drive it as mentioned above.. A+ for afRaceR.