V6 Engine runs strong in park, bogs/ has no power in gear

What is your question?

Happened suddenly, approx. 128,000 miles, runs strong in park or neutral (reasonably) idles rough stalls most times unless you step on accelerator, reaches 3000 or more rpms in park or neutral if pushed. In gear bogs down, no power even at full throttle. When it stalls out can usually smell gas and usually have to hold it to floor to start it. Car is currently running without exhaust, except for one catalytic converter (think it 's a cat) which is welded to manifold. Definitely sounds as if timing is off, backfires at higher rpms. Trying to fix myself not sure where to start, would like to resolve this issue before investing in exhaust system and other repairs. Do not have option of purchasing another car and cannot afford to take it to a mechanic. HELP!

What makes this problem better or worse?

maybe slightly when cold

How long has your 2000 Saturn LW2 had this problem?

happened some time ago but was not as bad, then a few days ago it got a lot, lot,worse, barely moves until it gets up a little momentum