Couple different intermittent problems w/ CEL and P0102 code

Hi, thank you so much for any help/advice in advance, I have posted for help on about 5 different sites and not received not even 1 response. I began to notice some hesitation on light acceleration the car would jerk a little almost like running out of gas, next problem was when starting; 1st start of the day or after sitting several hours car would start and hold idle just fine, then as soon as the car was warmed up car would turn fine but as soon as it started stall out unable to hold an idle, if I gave it a little gas for about 10 seconds or longer and forced it to hold an idle it would be fine after, last problem car would suddenly upshift hard, sometimes very hard and make the car jerk big time, most of the time if I pulled over and let the car cool down for ten minutes or so the hard shifting would stop for a little bit or sometimes even go away for a day or two. 1st I syphened some tranny fluid out through the fill hole (very red, healthy looking, no noticeable metal in fluid) and put in a quart of some transfix fluid stuff, car has shifted wonderfully for two months, in last two days have noticed just a couple of delayed shift times, feels like it grabs for just a second. I had my battery tested while having a tire repaired about two weeks ago and it was cranking very low so I replaced it and since have not a single time had a problem with holding an idle at start, car fires and holds idle perfect cold and hot. Still have occasional stuttering but not frequently at all maybe every few days and only once or twice. I replaced the MAFS, MAPS, TPS, IDLE AIR CONTROL VALVE, I've had the CEL code pulled and it's P0102 MAFS/LOW FREQUENCY or circuit something (can't remember exactly what the second part said) every time I clear the code it comes back within a couple of hours. I would guess that some of my issues are unrelated but I wanted to provide as much info as possible. It is close to $300 for an OEM MAFS so the replacement I used is an aftermarket one that I bought online for about 25bux. I just ordered a multimeter to check the wires, if it is an issue with the wiring will I be able to splice new wire to the MAFS plug? Is it hard to replace the wires completely? When replacing the Idle air control valve I noticed the carbon build up was pretty thick, I made a quick attempt at cleaning the throttle body, but that screen prevents a good cleaning without removing the throttle body, I have read mixed opinions regarding the removal of the screen, is it ok to take it off? How about removing it just to clean the throttle body is it easy to put back on? Any ideas why I'm still throwing the MAFS code? How do I check for a vacuum leak that would cause this code? Sorry for the lengthy post, and that you so much for any help. -Matthew