running issue 4.6

I am having a running issue with my 4.6 p38. It won't rev past 1800rpm and if i can get it to around that rpm it satrts to pop like its miss firing.

History

The wife was out in the rangey when it over heated for no apparent reason. The AA recovered the rangey home where by i checked the compression and there was very little on the one bank and mayo on that side idicating that the gasket was dead. On getting the head off there was no sign of cracking or distorsion but 5 out of the 8 valve stem seals were not seated. I changed the valve stem seals on both heads and then reassembled them removing the LPG system wiring after a previous problem with the lpg.

I have run another compression test to which the one bank read 7bar and the other 9bar so there is still an issue so where but this shouldnt stop it from revving. On the other hand it now idles better than ever.

Is there anyone that maybe able to shine some light on my problem

try getting it hot and take your maf
senser off, as it sounds like your maf is fooooked..

just tried the rangey. When cold she is fine and smooth but once warm the fault is back. I disconnected the MAF and the fault is still there. So i take it that this means that the maf is at fault??

is there anyway of cleaning the maf???

On the GEMS you can get access to the MAF sensor by cutting the rivets off the housing then it just slides out, clean it with some isopropyl alcohol.

Don't know about the THOR though!

what reading should i get from the MAF on a multimeter?? does anyone know?? I have ordered a replacement but i am not confident that this is the problem reading other MAF posts.