AnotherDeadCylinder

I'm hoping someone can help me narrow down what might be wrong with my car, because I am running out of ideas. The idle only acts up when I take my car out of gear while I'm comng to a stop. The idle fluctuates between 500 and 850 rpms until I have come to a complete stop. When the idle dips below 650, the alternator stops charging, my lights dim, and the battery voltage drops. The volts come back up when it bounces about 650 rpms. Depending on how long it takes me to stop, it usually bounces back and forth between 500 and 850 about 6 times before it returns to normal. The engine has not stalled while this is happening, but it is becoming more frequent. So far, I have replaced the MAF, TPS, IAC, and tested for a vacuum leak. Does anyone have any idea what might be causing this?

RockinWs6

How many miles on this car? Is it auto or manual? Any mods?

AnotherDeadCylinder

The car just reached 90K miles, transmission is a T5 manual, it's cammed with supporting mods (130# valve springs, double roller timing chain, ls7 lifters). It also has aftermarket headers and exhaust. I put did the mods when the car was at 76K miles, and this issue is just showing up now. I'm thinking it may be the crank position sensor, but I'm not sure.

RockinWs6

Did you check the coolant level? The TB maybe freezing up. Also check the fuel pressure.

AnotherDeadCylinder

I checked out the coolant, and it turns out it is low. It's kinda chucky looking too, so I'm going to do a radiator flush, as well as some brake work. Once that is done, I will check the fuel pressure. What kind of numbers should I be looking for with the fuel pressure, and should I be looking at certain RPMs? Thanks again for the help.

RockinWs6

If the engine was cammed then I'm assuming it has the updated intake gaskets? Be sure they are not leaking vacuum or coolant, if they are anything could be happening. Sorry I don't know the fuel pressure ratings but if you search on line you'll find them easily.