Diagnosis Needed - Oldsmobile Fouling Out

I have a 1998 Oldmobile Eighty Eight. It has a 3800 Series II 3.8L V6 engine w/ 80,000 miles. It was running great and it just fouled out. We replaced the plugs because they were a mess and were covered with oil. At the same time, we replaced the battery because it was swollen and old and the starter was replaced too. After doing all of this, the engine ran great for about a minute then it fouled out again going out slowly like it was running out of gas. The new plugs are now evenly covered with oil. There were no noises before the engine stopped either time. No rattling or clacking. We suspect a cracked intake manifold, but would rather find someone who has run into this problem before pulling everything apart.

Cracked intake manifold wouldnt cause that. Is it all the plugs or just a few? Any oil in the coolent/coolent in the oil?

Thanks for your response.

There might be coolant mixing with gas which would make it look like oil. How can you tell - Can you recommend a way to figure this out? All of the spark plugs are evenly covered with fluid. The engine ran perfectly for about a minute then just sputtered out as though it was out of gas. Checked the new plugs after that and they were all covered with fluid. There is a TSB out for this model which discusses a problem with coolant leaking into the intake. If this is the case, should we just replace the whole upper intake? Any special considerations?

Also, does anyone have a full text copy of the TSB? I can only find summaries online and can't wait to order a copy from the NHTSA.

check your local GM dealer, this MAY be under recall for your intake manifold. the egr passage inside the intake manifold melts the plastic intake and you get coolant contamination in your intake. it would be worth a check i think