2000 Rodeo question

I have a 2000 Rodeo with a 4 banger and about 75000 miles. It has had a good service record. I now notice after driving about 10 miles it lays down a short smoke screen, wants to quit running and then goes back to it's normal. Fluid levels are staying the same, so unsure what the problem may be. Plugs are not fouled, no noticeable leaks on or around the engine. Any help most appreciated. One mechanic told me it was a blown engine which I doubt as it runs fine, with no banging or loss of fluids just the smoke and hesitation. Thanks in advance