Ok so I have a 01 Blazer 4x4 A.T with 124,000 miles. I bought it and it would not go more the 7 mph it kinda just seemed like it was in N as I pressed the gas... The RPM's would go up real high as I pressed the gas but would only go as high as 7 MPH. I got no codes with a ODB 2 meter at that time... So I decided to change the transmission fluid and filter etc. There were no metal shaving in the pan and was somewhat clean but had a real dirty filter... Now It will go about 30 mhp but it seems its not shifting into 3rd I take it... I did run the OBD-2 meter after that and I got codes PO300- (Random/multiple cylinder misfire detected) and PO453-(EVAP emission control system pres sensor high) My uncle does not think that either one of them codes would cause this issue.... Any Ideas