anyone help? cars running rough after coolant flush

Ive just changed thermo n fan swtch for low temp ones, and after flushing and bleeding the system, ive found on a drive the car drives well in respect of cooling, (temperature never goes past thrid mark) and the fan cuts in earlier as expected.
But under acceleration, the engine seems to be holding back, like it wa a 1.6 or sumthing. At points it frees up, but seems a little juddery. The doesnt judder harshly, just seems to be holding back on power, then full bhp comes through, only to die off again. Anyone got any ideas? IM thinking maybe theres sum air in system...But after a drive and idle, if i slowly remove the expansion tank cap, not very much hissing is heard..surely any air wud be pushed to top of expaion tank? ideas please.

dont see how the coolant system would affect running unless it was either majorly hot, or majorly cold. You may have spilt some coolant on a sensor or plug, have you checked your dizzy, coolant temp sensor, leads etc.?

sounds like you got somthing wet when you flushed your system, would check that things are dry as this can cause problems

put my money on CAS http://www.barryboys.co.uk/phpBB2/im...es/popcorn.gif

whatever it was, seems to have gona away and runs fine now afer a second drive. could well have been some infector cleaning stuff I put through it. maybe that has to flush round first....anyway, has gone now. Findings after low temp thermo n fanswitch? Thermo suprisingly hasnt done an awful lot, seems to run a bit lower temp, but no that much lower, but the fan does kick in a hell of alot earlier.