I have a 1994 Ford Exploder 4.0l V6 Pushrod.
True Dual Exhaust - Dual in/out HiFlow Cat, Dual in/out Flowmaster 40
19lb Inj (stock)
K&N Cold Air Intake
66mm Throttle Body
55mm(stock) Mass Air Flow Sensor
3000cfm E-fan set at 180
I changed: (all has about 400 miles on it right now)
I dropped the tranny pan, fluid/filter, normal for 105,000 miles.
Oil and Filter
8mm plug wires
Cold or Warm when in park it Idles just fine @ 950rpm.
Place it in Drive it idles fine @ 500rpm.
Start driving and go over 3000rpm, then stop, keeping it in Drive, the idle moves (sudders) between 400-550rpm.
Now while its doing this if you take your foot off the brake to let it move @ idle,
every time it sudders it tries to stop the forward motion.
Place it back into Park and it goes away...
T-converter trying to lock up?
Bad valve that only shows at low idle?