Transmission Question

1999 Plymouth SOHC Automatic 125,000 miles

The transmission is stuck in the "Passing gear" or "overdrive" and i know i have to clean that area up and might have to get a new cable assembly.

It is stuck in pretty much the floored position by the way

BUT... does the transmission affect the cars PCM at all? Like making it fire later or something causing my rough idle?

The neon's 3-speed auto transmission doesn't have overdrive. It does have a lockup torques converter that will engage at highway speeds to decrease heat in the tranny and to help out on gas mileage.

The PCM does not control the car's tranny other than looking for the lockup torque converter and engaging it.

Is your CEL lit?

on the throttle lever there is a cable that is on the bottom below the accerator cable. when you give it more gas than usual driving it pulls the cable which puts the Transmission in a passing gear and it is currently stuck there so im driving at higher rpms than normal. if this stuck there and the transmission affects how the PCM controls the engine could this be causing my problem?

When you floor the pedal and put the engine at WOT, the transmission will downshift in order to pass cars. Having the engine add more fuel to the car will not cause a rough idle, but rather to idle higher than normal.

so pretty much only ill effects of being stuck there is bad mpg and lots of spinning on ice/snow.

What is the possibility that the timing belt is off a few notches or was not lined up correctly?

also is there any way to check this without having to remove the harmonic balancer and all that?

Rough idle could be lots of problems. MAP/IAT sensor, sticky TB, fuel injectors, gummed up fuel rail.

Do you have a CEL?

no CEL and doing the key dance only brings up 12 and 55 which are battery disconnected and end of codes.

only thing i can tell is cylinder #2 is dead at idle but a feather touching the gas pedal straightens out.

If one cylinder is dead at an idle, but works okay above idle - I would do a compression check, have a look at the spark plugs, maybe change that plug and plug wire.
A valve that is bent or not closing fully, or has a small chunk jammed between valve/seat, or has a sticking lifter, could result in blow back into the intake manifold - and might make the rough.

yeah i believe it has a bad exhaust valve on that one cause when i hold a dollar up to the tailpipe it tried to suck it in (Old way of quickly checking for bad valve) but ive been driving it like that for now and its not getting worse so ill leave it till it either gets worse or it gets warmer here (15 Degrees F and snowing) then ill pull the valve cover and check it out and do a compression check then.