Overheating and rough running will go hand in hand. I’d try to fix the overheating first, and see if it makes it run smoother.
Gets hot at low RPMS? Probably waterpump, maybe a plugged coolant passage. Obvious one: enough engine coolant? Next time it gets hot, put the heater on “hot” and crank it full blast. If it’s not very warm, heater core could be plugged (reducing flow to rest of engine) or there’s just steam floating around in your pipes (surprisingly, steam doesn’t make your heater core too warm). If your heat is extremely hot when you turn on the heater, then you’ve got water. Gets cold quickly after you turn on the heater? No flow.
If the heater acts like it’s supposed to, then your thermostat might not be opening. Start your engine cold, and take the rad cap off. If the water is not an inch or so below the first couple rows on your rad, then take a bit out. As it warms up, look into the radiator to watch for water coming out of those top few rows. No flow, the t-stat probably isn’t opening, or the water pump is gonzoed. You can take a hose off your heater core and start your engine. Water should gush out, or your water pump definitely isn’t working too well.
If it’s overheating, definitely look into the problem. Sadly, Cai lost an engine due to overheating a few days after installing it. It started to run really rough, and he figured it was a fueling problem and tried to ride it out. His engine went nuclear–melted the bearings.
Running hotter at low RPMs is a fairly normal condition. More RPMs of motor = more RPMs of rad fan.
If your coolant level is down at all, could possibly be an internal headgasket coolant leak. Would also explain rough running. Pull your spark plugs and check the condition, also check to see if your engine oil is getting discoloured.
Keep in mind Eso that I run a serpentine belt and the rad fan is electric at constant speed
Heat is HOT when on, coolant is good level and consentration, I also think it’s probably a plugged jacket, worn rad hose or worn impeller. As fo the thermostat, if the water level in the resevoir rises and falls normally with temperature, does the mean it is working alright?
Smokin’ warm dude. If you run the car for 10-15 minutes, you really gotta be carefull opening the cap. It pressurizes very quickly. I remember my old man popping my hood and pulling off the cap, it blew off into the bushes somewhere and covered him in boiling coolant. Neither of us were impressed.
