random rough idle and occasional white smoke

[totman]

I have a 94.5 f350 and recently have been getting rough idle at start up and occasionally at stop signs. Rough idle goes away if I rev it up a little. Also will get white smoke at higher rpms. Truck has extremely high mileage but has always been well cared for. It's never let me down and I'd like to keep her running top notch. Any ideas? I replaced the fuel filter like 12,000 miles ago but will probably replace it again here soon along with cleaning out the fpr. I did the fpr bb mod a few months back and it really woke her up.

[BigFuel]

Are you still good on coolant? Could be a sticking injector, faulty IPR, faulty CPS, or/and a bad HPOP

Personally, if the coolant is full and clean (sniff for diesel), I'd start testing the IPR and HPOP. The Ipr needs a scan tool that reads live data. Here is a quick thread on testing the HPOP:

hpop pump

[totman]

Radiator leaks a little so I'm consistently checking/adding coolant. Would the condition of the coolant cause the issues I've been having?

[BigFuel]

It would if you had a damaged head/block as the coolant isn't compressible in the cylinder and has to "steam" off. This will give off a sweet smell to the exhaust and will stutter the engine. Alternatively, A cracked injector cup could be leaking fuel into the coolant and allowing that injector to pulse with less atomization of the fuel into the cylinder again causing a stutter and fuel in the coolant.