Originally Posted by mustangman

first check for vaccum leaks,and for sure replace MAP sensor and check for vaccum going to it, your f53? if its a classA motorhome, might qualify for the free updated ecm/catalytic under recall#94b37 ,, my 92 f53 qualified but i never did or will never take it in, mine runs fine plus the newer ecm is programmed a bit leaner for emmisions, but main reason i don't take it in is they confiscate the original ecm and i don't trust tem with my sht, plus i went with full length Banks headers ditched the cat, if this ecm goes out i have one for a efi460/c6 going to ditch that e4od trans one day when it goes out and get a c6, update i just checked covers f53s built up to Jan-31-93,,go to you ford truck dealer give them your vin#, im betting its ur map sensor, they don't throw codes at times when they go