if there are codes in the computer,they are still there even if the light isnt on..
from the way you explain the problem,it doesnt sound to me as if it is a problem with the exhaust
from the way you explain,you need to test the fuel pressure,these must have no less than 60psi at all times,to me,it sounds as if your fuel pump may be weak and sticking at times.
the fuel pump
1- scan the computer for trouble codes
2- check the fuel pressure
If you are satisfied with my answer, Please Rate my answer by clicking the rating button so I can get credit for my work. I’m not always going to be giving you good news, so please don't let this stand in the way of you accepting my answer. .it does not cost you more money and we will still be able to communicate, ,.please understand, i can not see, hear or touch the vehicle and only know what you tell me. Bonuses and positive feedback are appreciated.. if you are not satisfied with my answer, please do not leave bad feed back ,i will gladly opt out and let another expert handle the question. .if i have sent any diagrams, please print them. .sometimes you may need to right click the image [,then save picture as]to save it to your computer so you can open it with your picture program...Please ask if you need more help.