Please Help trouble codes p2187 and p2195

[ok52989]

I recent came to possess a 2005 mazda 6. It threw three codes p0134-no activity o2 sensor, p2187- stuck lean, p2195 too lean idle. I replaced the O2 sensor and now I am just showing the p2187 and p2195. I have been able to put together that there is probably a vacuum leak, or the pgr valve may need to be replaced. I cleaned the MAF it helped but still idles rough. Also from a stop if i just tap the accelerator the car shudders and sort of revs up. When I have the car in park it doesnt idle steadily constantly going between two rpms altho not like before i replaced the o2 sensor. At that point it would idle fine for about 3 minutes before shuddering as if to stall. Any pointers or direction would be greatly appreciated.