Cars got no vavavoom!

I wonder if anyone can help me, ive got a laguna 1998 1.8, when ticking over it sounds like something is blocked as it struggles, when i pull off i get no power at all till i creep up to about 4000 revs then the engine kicks in and i get the power but sometimes i never get any power and have to crawl around, please help as it is driving me crazy!! :banghead:

got a 1.8 98 laguna havin the same problem did u find out what it was plz?