Well bro, i read your prob....this probelm is very common in steermatic and prosmatec vehicles....specially when you convert them to CNG.....and for this reason CNG is not recommended in these kinds of vehicles..
Anyways, there is no need to panic about the prob...neither do u need to waste money with defence motors nor do u need to get ur transmission replaced.....just there are a few points that are not clear to me......so just give me a call any time.....after clearing those...I will tel you what to do.
Take care..
Walleed
Neat Autos, Islamabad
0303-5583065