bogging

Well heres a story.. I went to go get my windows tinted , and stopped for coffee . When i jumped back in my car (1.8 b15 i think u guys call it) my power steering was gone . So i checked my fluid , and it was all good , and i had to be at my appointment so i got the car there . About 4 hours later when they where done i was driving home , and then all of a sudden the car just bogged down , and lost almost all engine power . (It was reving lower then idol) so i let the my foot off the gas , and it powred up to an idle , and I tried again , but it bogged out again . So i went down into 4th , and the same thing . i tried it in first , and i got up to 20 Kmh , and the car started to bog again . Shutting the car off solved the problem , and I drove it home . I cant say exactly what the revs where at though because i dont have an rpm gauge , and now i got a solid service engine soon light . Powersteering is fixed . It was a snapped belt, but this other part is getting the best of me . Any ideas why it bogged , why it doesnt do it no more , and why the service engine light . I was told from the people at a nissan dealership that the solid light is not a big deal , but i am still pretty concerned

Check your fuel pressure with just the ignition turned on and then with the engine running.