1991 Ford Explorer hard to start

1997 Ford Explorer XLT 4.0 SOHC hard start. Cranks every time, starts after the 7th or 8th time. Once started, it chugs. Turn it off and get it to start again and seems to run fine after it warms up. Once in awhile if I go before it is warm, it seems like there is a weird shift in tranny. It will go into next gear, then back down and back into that gear again. When it shifts that way, it is immediate that it goes in, drops back to lower gear and back into higher gear. There is no lack of shifting either way. No grinding or sincro issues that I can hear. I didn't have the starting or tranny issue until a week ago when I had my thermostat housing and Temp sensors replaced. What could they have hit and knocked loose, or broke in the process of loosening intake to get to sensors and therm housing? I (myself) replaced the $283 air inlet hose because I thought that was it, but still does the same. They ripped it in the process and never said a word about taping it up. That is the reason I replaced it. My check engine light has been on since therm housing repair. I went to Advance Auto parts and had them check the code, and one of the sensors that I just paid to replace is bad, or the wrong one. No other code is being thrown. At this point, I will replace that sensor myself so this dingbat mechanic doesn't cause anymore damage to my truck. Thanks a bunch guys! =]