Driving from Eureka Springs AR to Marshfield MO (hilly and curvey) Check Engine Light came on.... no matter how much I accelerated or tried to wouldn't come out of gear or accelerate.  Come to a decline in road check engine light goes off and able to accelerate, back to level or incline check engine light back on and no acceleration. Thinking this may be a transmission problem, just had serviced in October and it was reading about 3/4 full on dipstick.  Talked to a neighbor with a fifth wheel said he had issues with his diesel because of Bio Diesel..... is this possible with my CAT?  He puts  preventive in his fuel now.... 

Have an apt with the Allison Transmission guy on Monday..... am I going the wrong direction?

Thanks for any and all assistance!

Jeff