Have this happening currently, had my engine replaced with a factory re-man @ 208,000. at that time also replaced exh. gaskets and seals,all hoses, water pump, thermostat, engine mounts, op sensor, starter, alternator, rad cap and ov flw tank, drv. belt, pulley and tensioner, plugs and wires, temp sensor, dipstick tube, and cam position sensor. whew!
Any how few months later, kept getting rough idle and low oil pressure at every stop but since I am a woman nobody believed me "Nothing Wrong , Normal" .
Forward 1 year later (not sure of the mileage here) still happening and 30 miles away from home I get a check engine lite and call onstar they say I'm ok to drive home and take to dealer... Now driving home on freeway 40 mph, in limp mode, in slow lane all the way ...
At dealer they check out and re-man engine was put together from plant wrong ( on a Friday lol ) So I get it newly rebuilt from dealer..
Now at 280,000+ miles over 4 years and out of warranty and still have this rough idle and low op at stops and STILL getting told this is normal... REALLY ! It runs fine at go. op at 40 but once stopped it immediately idles rough and op drops to about 25.
Anybody else have/had this issue and gotten it fixed?? New engines should NOT have this issue.