sputter stall when I step on the gas 1997 850R

[That850Rbaby]

Just recently, The check engine light came on in my car, I spoke with a dealer mechanic and was told it was most likely a loss of power issue. Since then the check engine light went off by itself. When I tried to accelerate hard it popped back on. When I put my foot down on the gas hard it would hesitate then kick in. I put fuel injector cleaner into my gas tank and after about a 100 miles or so it started to sputter as seriously lose power. I was cruising around 50 mph when I tried to accelerate to 60 and it began stuttering I let off the gas and it worked. I was able to accelerate slowly to 70mph. The next time I drove it it worked but it idled hard and worked fine for the first five miles then as I started up a hill and gave it more gas it stuttered and stalled out. when I tried to start it, it turned over, sputtered and stalled. When I tried to step on the gas it did the same thing. I then turned off the lights and and the radio inside the car I also turned off the headlights. When I started it stayed on sputtering. I dropped it into low gear and it got stronger. I was able to drive it back home at around 25 mph or so. I put it in park and revved the engine and it worked fine. What does the problem sound like it could be? And are there alternative fixes?

[F18]

I am sure others will pipe in.....but the fact that a CEL is coming on means there should be some codes stored in the OBDll system that will help you narrow it down. Try getting the codes read at Autozone or borrow a OBDll code reader.
It could be any number of things.... sensor issues (particularly a dirty MAF)
A clogged fuel filter but that should not through a CEL but it could aggrevate another problem that would. Or it could be a simple vacumm leak. But it would be all a guess until you get the diagnostic codes read.
Let us know more...
Cheers,
FRED